diff --git a/curve25519-dalek-derive/Cargo.toml b/curve25519-dalek-derive/Cargo.toml
index 938144a0f..aed791c78 100644
--- a/curve25519-dalek-derive/Cargo.toml
+++ b/curve25519-dalek-derive/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2021"
 repository = "https://github.com/dalek-cryptography/curve25519-dalek"
 homepage = "https://github.com/dalek-cryptography/curve25519-dalek"
 documentation = "https://docs.rs/curve25519-dalek-derive"
-license = "MIT/Apache-2.0"
+license = "MIT OR Apache-2.0"
 readme = "README.md"
 description = "curve25519-dalek Derives"
 
diff --git a/curve25519-dalek-derive/tests/tests.rs b/curve25519-dalek-derive/tests/tests.rs
index 1516b3527..dce30c864 100644
--- a/curve25519-dalek-derive/tests/tests.rs
+++ b/curve25519-dalek-derive/tests/tests.rs
@@ -23,10 +23,6 @@ where
     a - b
 }
 
-#[unsafe_target_feature("sse2")]
-#[cfg(feature = "dummy")]
-fn function_with_cfg() {}
-
 #[unsafe_target_feature("sse2")]
 #[rustfmt::skip]
 fn function_with_rustfmt_skip() {}
@@ -45,9 +41,6 @@ impl Struct {
     fn member_function_with_const_arg<const N: u32>(self) -> u32 {
         self.a - N
     }
-
-    #[cfg(feature = "dummy")]
-    fn member_function_with_cfg() {}
 }
 
 struct StructWithGenerics<T>
@@ -93,7 +86,7 @@ mod inner {
     }
 }
 
-#[unsafe_target_feature_specialize("sse2", "avx2", conditional("avx512ifma", disabled))]
+#[unsafe_target_feature_specialize("sse2", "avx2")]
 mod inner_spec {
     #[for_target_feature("sse2")]
     const CONST: u32 = 1;
diff --git a/curve25519-dalek/CHANGELOG.md b/curve25519-dalek/CHANGELOG.md
index a4c8452cc..939d3bfba 100644
--- a/curve25519-dalek/CHANGELOG.md
+++ b/curve25519-dalek/CHANGELOG.md
@@ -5,6 +5,11 @@ major series.
 
 ## 4.x series
 
+### 4.1.3
+
+* Security: Fix timing leak in Scalar subtraction on u32, u64, fiat_u32, and fiat_u64 backends
+* Fix assorted new warnings and lints from rustc and clippy
+
 ### 4.1.2
 
 * Fix nightly SIMD build
diff --git a/curve25519-dalek/Cargo.toml b/curve25519-dalek/Cargo.toml
index ea640e862..e09aada2f 100644
--- a/curve25519-dalek/Cargo.toml
+++ b/curve25519-dalek/Cargo.toml
@@ -4,7 +4,7 @@ name = "curve25519-dalek"
 # - update CHANGELOG
 # - update README if required by semver
 # - if README was updated, also update module documentation in src/lib.rs
-version = "4.1.2"
+version = "4.1.3"
 edition = "2021"
 rust-version = "1.60.0"
 authors = ["Isis Lovecruft <isis@patternsinthevoid.net>",
@@ -38,7 +38,6 @@ rand = "0.8"
 rand_core = { version = "0.6", default-features = false, features = ["getrandom"] }
 
 [build-dependencies]
-platforms = "3.0.2"
 rustc_version = "0.4.0"
 
 [[bench]]
@@ -52,7 +51,7 @@ ff = { version = "0.13", default-features = false, optional = true }
 group = { version = "0.13", default-features = false, optional = true }
 rand_core = { version = "0.6.4", default-features = false, optional = true }
 digest = { version = "0.10", default-features = false, optional = true }
-subtle = { version = "2.3.0", default-features = false }
+subtle = { version = "2.6.0", default-features = false, features = ["const-generics"]}
 serde = { version = "1.0", default-features = false, optional = true, features = ["derive"] }
 zeroize = { version = "1", default-features = false, optional = true }
 
@@ -70,8 +69,15 @@ legacy_compatibility = []
 group = ["dep:group", "rand_core"]
 group-bits = ["group", "ff/bits"]
 
-[target.'cfg(all(not(curve25519_dalek_backend = "fiat"), not(curve25519_dalek_backend = "serial"), target_arch = "x86_64"))'.dependencies]
+[target.'cfg(all(not(curve25519_dalek_backend = "fiat"), not(curve25519_dalek_backend = "serial"), any(target_arch = "x86_64", target_arch = "aarch64")))'.dependencies]
 curve25519-dalek-derive = { version = "0.1", path = "../curve25519-dalek-derive" }
 
-[target.'cfg(all(not(curve25519_dalek_backend = "fiat"), not(curve25519_dalek_backend = "serial"), target_arch = "aarch64"))'.dependencies]
-curve25519-dalek-derive = { version = "0.1", path = "../curve25519-dalek-derive" }
+[lints.rust.unexpected_cfgs]
+level = "warn"
+check-cfg = [
+    'cfg(allow_unused_unsafe)',
+    'cfg(curve25519_dalek_backend, values("fiat", "serial", "simd"))',
+    'cfg(curve25519_dalek_diagnostics, values("build"))',
+    'cfg(curve25519_dalek_bits, values("32", "64"))',
+    'cfg(nightly)',
+]
diff --git a/curve25519-dalek/build.rs b/curve25519-dalek/build.rs
index eca17c02d..17b436308 100644
--- a/curve25519-dalek/build.rs
+++ b/curve25519-dalek/build.rs
@@ -9,17 +9,31 @@ enum DalekBits {
     Dalek64,
 }
 
+use std::fmt::Formatter;
+
+impl std::fmt::Display for DalekBits {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), std::fmt::Error> {
+        let w_bits = match self {
+            DalekBits::Dalek32 => "32",
+            DalekBits::Dalek64 => "64",
+        };
+        write!(f, "{}", w_bits)
+    }
+}
+
 fn main() {
+    let target_arch = match std::env::var("CARGO_CFG_TARGET_ARCH") {
+        Ok(arch) => arch,
+        _ => "".to_string(),
+    };
+
     let curve25519_dalek_bits = match std::env::var("CARGO_CFG_CURVE25519_DALEK_BITS").as_deref() {
         Ok("32") => DalekBits::Dalek32,
         Ok("64") => DalekBits::Dalek64,
-        _ => deterministic::determine_curve25519_dalek_bits(),
+        _ => deterministic::determine_curve25519_dalek_bits(&target_arch),
     };
 
-    match curve25519_dalek_bits {
-        DalekBits::Dalek64 => println!("cargo:rustc-cfg=curve25519_dalek_bits=\"64\""),
-        DalekBits::Dalek32 => println!("cargo:rustc-cfg=curve25519_dalek_bits=\"32\""),
-    }
+    println!("cargo:rustc-cfg=curve25519_dalek_bits=\"{curve25519_dalek_bits}\"");
 
     if rustc_version::version_meta()
         .expect("failed to detect rustc version")
@@ -36,11 +50,6 @@ fn main() {
         println!("cargo:rustc-cfg=allow_unused_unsafe");
     }
 
-    let target_arch = match std::env::var("CARGO_CFG_TARGET_ARCH") {
-        Ok(arch) => arch,
-        _ => "".to_string(),
-    };
-
     // Backend overrides / defaults
     let curve25519_dalek_backend =
         match std::env::var("CARGO_CFG_CURVE25519_DALEK_BACKEND").as_deref() {
@@ -74,11 +83,12 @@ mod deterministic {
 
     use super::*;
 
-    // Standard Cargo TARGET environment variable of triplet is required
-    static ERR_MSG_NO_TARGET: &str = "Standard Cargo TARGET environment variable is not set";
+    // Custom Rust non-cargo build tooling needs to set CARGO_CFG_TARGET_POINTER_WIDTH
+    static ERR_MSG_NO_POINTER_WIDTH: &str =
+        "Standard Cargo TARGET_POINTER_WIDTH environment variable is not set.";
 
-    // Custom Non-Rust standard target platforms require explicit settings.
-    static ERR_MSG_NO_PLATFORM: &str = "Unknown Rust target platform.";
+    // When either non-32 or 64 TARGET_POINTER_WIDTH detected
+    static ERR_MSG_UNKNOWN_POINTER_WIDTH: &str = "Unknown TARGET_POINTER_WIDTH detected.";
 
     // Warning when the curve25519_dalek_bits cannot be determined
     fn determine_curve25519_dalek_bits_warning(cause: &str) {
@@ -86,41 +96,30 @@ mod deterministic {
     }
 
     // Determine the curve25519_dalek_bits based on Rust standard TARGET triplet
-    pub(super) fn determine_curve25519_dalek_bits() -> DalekBits {
-        use platforms::target::PointerWidth;
-
-        // TARGET environment is supplied by Cargo
-        // https://doc.rust-lang.org/cargo/reference/environment-variables.html
-        let target_triplet = match std::env::var("TARGET") {
-            Ok(t) => t,
+    pub(super) fn determine_curve25519_dalek_bits(target_arch: &String) -> DalekBits {
+        let target_pointer_width = match std::env::var("CARGO_CFG_TARGET_POINTER_WIDTH") {
+            Ok(pw) => pw,
             Err(_) => {
-                determine_curve25519_dalek_bits_warning(ERR_MSG_NO_TARGET);
-                return DalekBits::Dalek32;
-            }
-        };
-
-        // platforms crate is the source of truth used to determine the platform
-        let platform = match platforms::Platform::find(&target_triplet) {
-            Some(p) => p,
-            None => {
-                determine_curve25519_dalek_bits_warning(ERR_MSG_NO_PLATFORM);
+                determine_curve25519_dalek_bits_warning(ERR_MSG_NO_POINTER_WIDTH);
                 return DalekBits::Dalek32;
             }
         };
 
         #[allow(clippy::match_single_binding)]
-        match platform.target_arch {
+        match &target_arch {
             //Issues: 449 and 456
+            //TODO: When adding arch defaults use proper types not String match
             //TODO(Arm): Needs tests + benchmarks to back this up
-            //platforms::target::Arch::Arm => DalekBits::Dalek64,
             //TODO(Wasm32): Needs tests + benchmarks to back this up
-            //platforms::target::Arch::Wasm32 => DalekBits::Dalek64,
-            _ => match platform.target_pointer_width {
-                PointerWidth::U64 => DalekBits::Dalek64,
-                PointerWidth::U32 => DalekBits::Dalek32,
+            _ => match target_pointer_width.as_ref() {
+                "64" => DalekBits::Dalek64,
+                "32" => DalekBits::Dalek32,
                 // Intended default solely for non-32/64 target pointer widths
                 // Otherwise known target platforms only.
-                _ => DalekBits::Dalek32,
+                _ => {
+                    determine_curve25519_dalek_bits_warning(ERR_MSG_UNKNOWN_POINTER_WIDTH);
+                    DalekBits::Dalek32
+                }
             },
         }
     }
diff --git a/curve25519-dalek/src/backend/mod.rs b/curve25519-dalek/src/backend/mod.rs
index 61c93b0af..4fcc7f627 100644
--- a/curve25519-dalek/src/backend/mod.rs
+++ b/curve25519-dalek/src/backend/mod.rs
@@ -44,22 +44,22 @@ pub mod vector;
 
 #[derive(Copy, Clone)]
 enum BackendKind {
-    #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
+    #[cfg(all(curve25519_dalek_backend = "simd", target_arch = "x86_64"))]
     Avx2,
-    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
+    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "x86_64"))]
     Avx512,
-    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
+    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "aarch64"))]
     Neon,
     Serial,
 }
 
 #[inline]
 fn get_selected_backend() -> BackendKind {
-    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
+    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "aarch64"))]
     {
         return BackendKind::Neon;
     }
-    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
+    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "x86_64"))]
     {
         cpufeatures::new!(cpuid_avx512, "avx512ifma", "avx512vl");
         let token_avx512: cpuid_avx512::InitToken = cpuid_avx512::init();
@@ -68,7 +68,7 @@ fn get_selected_backend() -> BackendKind {
         }
     }
 
-    #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
+    #[cfg(all(curve25519_dalek_backend = "simd", target_arch = "x86_64"))]
     {
         cpufeatures::new!(cpuid_avx2, "avx2");
         let token_avx2: cpuid_avx2::InitToken = cpuid_avx2::init();
@@ -93,31 +93,29 @@ where
     match get_selected_backend() {
         #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
         BackendKind::Avx2 =>
-            self::vector::scalar_mul::pippenger::spec_avx2::Pippenger::optional_multiscalar_mul::<I, J>(scalars, points),
+            vector::scalar_mul::pippenger::spec_avx2::Pippenger::optional_multiscalar_mul::<I, J>(scalars, points),
         #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
         BackendKind::Avx512 =>
-            self::vector::scalar_mul::pippenger::spec_avx512ifma_avx512vl::Pippenger::optional_multiscalar_mul::<I, J>(scalars, points),
+            vector::scalar_mul::pippenger::spec_avx512ifma_avx512vl::Pippenger::optional_multiscalar_mul::<I, J>(scalars, points),
         #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
         BackendKind::Neon =>
-            self::vector::scalar_mul::pippenger::spec_neon::Pippenger::optional_multiscalar_mul::<I, J>(scalars, points),
+            vector::scalar_mul::pippenger::spec_neon::Pippenger::optional_multiscalar_mul::<I, J>(scalars, points),
         BackendKind::Serial =>
-            self::serial::scalar_mul::pippenger::Pippenger::optional_multiscalar_mul::<I, J>(scalars, points),
+            serial::scalar_mul::pippenger::Pippenger::optional_multiscalar_mul::<I, J>(scalars, points),
     }
 }
 
 #[cfg(feature = "alloc")]
 pub(crate) enum VartimePrecomputedStraus {
-    #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
-    Avx2(self::vector::scalar_mul::precomputed_straus::spec_avx2::VartimePrecomputedStraus),
-    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
+    #[cfg(all(curve25519_dalek_backend = "simd", target_arch = "x86_64"))]
+    Avx2(vector::scalar_mul::precomputed_straus::spec_avx2::VartimePrecomputedStraus),
+    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "x86_64"))]
     Avx512ifma(
-        self::vector::scalar_mul::precomputed_straus::spec_avx512ifma_avx512vl::VartimePrecomputedStraus,
+        vector::scalar_mul::precomputed_straus::spec_avx512ifma_avx512vl::VartimePrecomputedStraus,
     ),
-    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
-    Neon(
-        self::vector::scalar_mul::precomputed_straus::spec_neon::VartimePrecomputedStraus
-    ),
-    Scalar(self::serial::scalar_mul::precomputed_straus::VartimePrecomputedStraus),
+    #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "aarch64"))]
+    Neon(vector::scalar_mul::precomputed_straus::spec_neon::VartimePrecomputedStraus),
+    Scalar(serial::scalar_mul::precomputed_straus::VartimePrecomputedStraus),
 }
 
 #[cfg(feature = "alloc")]
@@ -132,15 +130,15 @@ impl VartimePrecomputedStraus {
         match get_selected_backend() {
             #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
             BackendKind::Avx2 =>
-                VartimePrecomputedStraus::Avx2(self::vector::scalar_mul::precomputed_straus::spec_avx2::VartimePrecomputedStraus::new(static_points)),
+                VartimePrecomputedStraus::Avx2(vector::scalar_mul::precomputed_straus::spec_avx2::VartimePrecomputedStraus::new(static_points)),
             #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
             BackendKind::Avx512 =>
-                VartimePrecomputedStraus::Avx512ifma(self::vector::scalar_mul::precomputed_straus::spec_avx512ifma_avx512vl::VartimePrecomputedStraus::new(static_points)),
+                VartimePrecomputedStraus::Avx512ifma(vector::scalar_mul::precomputed_straus::spec_avx512ifma_avx512vl::VartimePrecomputedStraus::new(static_points)),
             #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
             BackendKind::Neon =>
-                VartimePrecomputedStraus::Neon(self::vector::scalar_mul::precomputed_straus::spec_neon::VartimePrecomputedStraus::new(static_points)),
+                VartimePrecomputedStraus::Neon(vector::scalar_mul::precomputed_straus::spec_neon::VartimePrecomputedStraus::new(static_points)),
             BackendKind::Serial =>
-                VartimePrecomputedStraus::Scalar(self::serial::scalar_mul::precomputed_straus::VartimePrecomputedStraus::new(static_points))
+                VartimePrecomputedStraus::Scalar(serial::scalar_mul::precomputed_straus::VartimePrecomputedStraus::new(static_points))
         }
     }
 
@@ -160,20 +158,20 @@ impl VartimePrecomputedStraus {
         use crate::traits::VartimePrecomputedMultiscalarMul;
 
         match self {
-            #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
+            #[cfg(all(curve25519_dalek_backend = "simd", target_arch = "x86_64"))]
             VartimePrecomputedStraus::Avx2(inner) => inner.optional_mixed_multiscalar_mul(
                 static_scalars,
                 dynamic_scalars,
                 dynamic_points,
             ),
-            #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
+            #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "x86_64"))]
             VartimePrecomputedStraus::Avx512ifma(inner) => inner.optional_mixed_multiscalar_mul(
                 static_scalars,
                 dynamic_scalars,
                 dynamic_points,
             ),
-            #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
-            VartimePrecomputedStraus::Neon(inner) =>  inner.optional_mixed_multiscalar_mul(
+            #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "aarch64"))]
+            VartimePrecomputedStraus::Neon(inner) => inner.optional_mixed_multiscalar_mul(
                 static_scalars,
                 dynamic_scalars,
                 dynamic_points,
@@ -199,27 +197,22 @@ where
     use crate::traits::MultiscalarMul;
 
     match get_selected_backend() {
-        #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
+        #[cfg(all(curve25519_dalek_backend = "simd", target_arch = "x86_64"))]
         BackendKind::Avx2 => {
-            self::vector::scalar_mul::straus::spec_avx2::Straus::multiscalar_mul::<I, J>(
-                scalars, points,
-            )
+            vector::scalar_mul::straus::spec_avx2::Straus::multiscalar_mul::<I, J>(scalars, points)
         }
-        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
+        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "x86_64"))]
         BackendKind::Avx512 => {
-            self::vector::scalar_mul::straus::spec_avx512ifma_avx512vl::Straus::multiscalar_mul::<
-                I,
-                J,
-            >(scalars, points)
-        }
-        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
-        BackendKind::Neon => {
-            self::vector::scalar_mul::straus::spec_neon::Straus::multiscalar_mul::<I, J>(
+            vector::scalar_mul::straus::spec_avx512ifma_avx512vl::Straus::multiscalar_mul::<I, J>(
                 scalars, points,
             )
         }
+        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "aarch64"))]
+        BackendKind::Neon => {
+            vector::scalar_mul::straus::spec_neon::Straus::multiscalar_mul::<I, J>(scalars, points)
+        }
         BackendKind::Serial => {
-            self::serial::scalar_mul::straus::Straus::multiscalar_mul::<I, J>(scalars, points)
+            serial::scalar_mul::straus::Straus::multiscalar_mul::<I, J>(scalars, points)
         }
     }
 }
@@ -235,29 +228,27 @@ where
     use crate::traits::VartimeMultiscalarMul;
 
     match get_selected_backend() {
-        #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
+        #[cfg(all(curve25519_dalek_backend = "simd", target_arch = "x86_64"))]
         BackendKind::Avx2 => {
-            self::vector::scalar_mul::straus::spec_avx2::Straus::optional_multiscalar_mul::<I, J>(
+            vector::scalar_mul::straus::spec_avx2::Straus::optional_multiscalar_mul::<I, J>(
                 scalars, points,
             )
         }
-        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
+        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "x86_64"))]
         BackendKind::Avx512 => {
-            self::vector::scalar_mul::straus::spec_avx512ifma_avx512vl::Straus::optional_multiscalar_mul::<
+            vector::scalar_mul::straus::spec_avx512ifma_avx512vl::Straus::optional_multiscalar_mul::<
                 I,
                 J,
             >(scalars, points)
         }
-        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
+        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "aarch64"))]
         BackendKind::Neon => {
-            self::vector::scalar_mul::straus::spec_neon::Straus::optional_multiscalar_mul::<I, J>(
-                scalars, points
+            vector::scalar_mul::straus::spec_neon::Straus::optional_multiscalar_mul::<I, J>(
+                scalars, points,
             )
         }
         BackendKind::Serial => {
-            self::serial::scalar_mul::straus::Straus::optional_multiscalar_mul::<I, J>(
-                scalars, points,
-            )
+            serial::scalar_mul::straus::Straus::optional_multiscalar_mul::<I, J>(scalars, points)
         }
     }
 }
@@ -265,15 +256,15 @@ where
 /// Perform constant-time, variable-base scalar multiplication.
 pub fn variable_base_mul(point: &EdwardsPoint, scalar: &Scalar) -> EdwardsPoint {
     match get_selected_backend() {
-        #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
-        BackendKind::Avx2 => self::vector::scalar_mul::variable_base::spec_avx2::mul(point, scalar),
-        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
+        #[cfg(all(curve25519_dalek_backend = "simd", target_arch = "x86_64"))]
+        BackendKind::Avx2 => vector::scalar_mul::variable_base::spec_avx2::mul(point, scalar),
+        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "x86_64"))]
         BackendKind::Avx512 => {
-            self::vector::scalar_mul::variable_base::spec_avx512ifma_avx512vl::mul(point, scalar)
+            vector::scalar_mul::variable_base::spec_avx512ifma_avx512vl::mul(point, scalar)
         }
-        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
-        BackendKind::Neon => self::vector::scalar_mul::variable_base::spec_neon::mul(point, scalar),
-        BackendKind::Serial => self::serial::scalar_mul::variable_base::mul(point, scalar),
+        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "aarch64"))]
+        BackendKind::Neon => vector::scalar_mul::variable_base::spec_neon::mul(point, scalar),
+        BackendKind::Serial => serial::scalar_mul::variable_base::mul(point, scalar),
     }
 }
 
@@ -281,14 +272,14 @@ pub fn variable_base_mul(point: &EdwardsPoint, scalar: &Scalar) -> EdwardsPoint
 #[allow(non_snake_case)]
 pub fn vartime_double_base_mul(a: &Scalar, A: &EdwardsPoint, b: &Scalar) -> EdwardsPoint {
     match get_selected_backend() {
-        #[cfg(all(curve25519_dalek_backend = "simd", target_arch="x86_64"))]
-        BackendKind::Avx2 => self::vector::scalar_mul::vartime_double_base::spec_avx2::mul(a, A, b),
-        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="x86_64"))]
+        #[cfg(all(curve25519_dalek_backend = "simd", target_arch = "x86_64"))]
+        BackendKind::Avx2 => vector::scalar_mul::vartime_double_base::spec_avx2::mul(a, A, b),
+        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "x86_64"))]
         BackendKind::Avx512 => {
-            self::vector::scalar_mul::vartime_double_base::spec_avx512ifma_avx512vl::mul(a, A, b)
+            vector::scalar_mul::vartime_double_base::spec_avx512ifma_avx512vl::mul(a, A, b)
         }
-        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch="aarch64"))]
-        BackendKind::Neon => self::vector::scalar_mul::vartime_double_base::spec_neon::mul(a, A, b),
-        BackendKind::Serial => self::serial::scalar_mul::vartime_double_base::mul(a, A, b),
+        #[cfg(all(curve25519_dalek_backend = "simd", nightly, target_arch = "aarch64"))]
+        BackendKind::Neon => vector::scalar_mul::vartime_double_base::spec_neon::mul(a, A, b),
+        BackendKind::Serial => serial::scalar_mul::vartime_double_base::mul(a, A, b),
     }
 }
diff --git a/curve25519-dalek/src/backend/serial/curve_models/mod.rs b/curve25519-dalek/src/backend/serial/curve_models/mod.rs
index d482d721a..1343d3706 100644
--- a/curve25519-dalek/src/backend/serial/curve_models/mod.rs
+++ b/curve25519-dalek/src/backend/serial/curve_models/mod.rs
@@ -527,7 +527,7 @@ impl<'a> Neg for &'a AffineNielsPoint {
 // ------------------------------------------------------------------------
 
 impl Debug for ProjectivePoint {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(
             f,
             "ProjectivePoint{{\n\tX: {:?},\n\tY: {:?},\n\tZ: {:?}\n}}",
@@ -537,7 +537,7 @@ impl Debug for ProjectivePoint {
 }
 
 impl Debug for CompletedPoint {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(
             f,
             "CompletedPoint{{\n\tX: {:?},\n\tY: {:?},\n\tZ: {:?},\n\tT: {:?}\n}}",
@@ -547,7 +547,7 @@ impl Debug for CompletedPoint {
 }
 
 impl Debug for AffineNielsPoint {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(
             f,
             "AffineNielsPoint{{\n\ty_plus_x: {:?},\n\ty_minus_x: {:?},\n\txy2d: {:?}\n}}",
@@ -557,7 +557,7 @@ impl Debug for AffineNielsPoint {
 }
 
 impl Debug for ProjectiveNielsPoint {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "ProjectiveNielsPoint{{\n\tY_plus_X: {:?},\n\tY_minus_X: {:?},\n\tZ: {:?},\n\tT2d: {:?}\n}}",
                &self.Y_plus_X, &self.Y_minus_X, &self.Z, &self.T2d)
     }
diff --git a/curve25519-dalek/src/backend/serial/fiat_u32/field.rs b/curve25519-dalek/src/backend/serial/fiat_u32/field.rs
index 94e1f6d36..97695c383 100644
--- a/curve25519-dalek/src/backend/serial/fiat_u32/field.rs
+++ b/curve25519-dalek/src/backend/serial/fiat_u32/field.rs
@@ -58,7 +58,7 @@ use fiat_crypto::curve25519_32::*;
 pub struct FieldElement2625(pub(crate) fiat_25519_tight_field_element);
 
 impl Debug for FieldElement2625 {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "FieldElement2625({:?})", &(self.0).0[..])
     }
 }
diff --git a/curve25519-dalek/src/backend/serial/fiat_u64/field.rs b/curve25519-dalek/src/backend/serial/fiat_u64/field.rs
index c871b55c2..2a022e23e 100644
--- a/curve25519-dalek/src/backend/serial/fiat_u64/field.rs
+++ b/curve25519-dalek/src/backend/serial/fiat_u64/field.rs
@@ -47,7 +47,7 @@ use fiat_crypto::curve25519_64::*;
 pub struct FieldElement51(pub(crate) fiat_25519_tight_field_element);
 
 impl Debug for FieldElement51 {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "FieldElement51({:?})", &(self.0).0[..])
     }
 }
diff --git a/curve25519-dalek/src/backend/serial/scalar_mul/pippenger.rs b/curve25519-dalek/src/backend/serial/scalar_mul/pippenger.rs
index 9af39e599..f60d9b953 100644
--- a/curve25519-dalek/src/backend/serial/scalar_mul/pippenger.rs
+++ b/curve25519-dalek/src/backend/serial/scalar_mul/pippenger.rs
@@ -164,7 +164,6 @@ impl VartimeMultiscalarMul for Pippenger {
 mod test {
     use super::*;
     use crate::constants;
-    use crate::scalar::Scalar;
 
     #[test]
     fn test_vartime_pippenger() {
diff --git a/curve25519-dalek/src/backend/serial/scalar_mul/precomputed_straus.rs b/curve25519-dalek/src/backend/serial/scalar_mul/precomputed_straus.rs
index 711649e21..53116c628 100644
--- a/curve25519-dalek/src/backend/serial/scalar_mul/precomputed_straus.rs
+++ b/curve25519-dalek/src/backend/serial/scalar_mul/precomputed_straus.rs
@@ -75,7 +75,7 @@ impl VartimePrecomputedMultiscalarMul for VartimePrecomputedStraus {
 
         let sp = self.static_lookup_tables.len();
         let dp = dynamic_lookup_tables.len();
-        assert_eq!(sp, static_nafs.len());
+        assert!(sp >= static_nafs.len());
         assert_eq!(dp, dynamic_nafs.len());
 
         // We could save some doublings by looking for the highest
@@ -99,7 +99,7 @@ impl VartimePrecomputedMultiscalarMul for VartimePrecomputedStraus {
             }
 
             #[allow(clippy::needless_range_loop)]
-            for i in 0..sp {
+            for i in 0..static_nafs.len() {
                 let t_ij = static_nafs[i][j];
                 match t_ij.cmp(&0) {
                     Ordering::Greater => {
diff --git a/curve25519-dalek/src/backend/serial/u32/field.rs b/curve25519-dalek/src/backend/serial/u32/field.rs
index 4e0b2133b..7319288a0 100644
--- a/curve25519-dalek/src/backend/serial/u32/field.rs
+++ b/curve25519-dalek/src/backend/serial/u32/field.rs
@@ -54,7 +54,7 @@ use zeroize::Zeroize;
 pub struct FieldElement2625(pub(crate) [u32; 10]);
 
 impl Debug for FieldElement2625 {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "FieldElement2625({:?})", &self.0[..])
     }
 }
diff --git a/curve25519-dalek/src/backend/serial/u32/scalar.rs b/curve25519-dalek/src/backend/serial/u32/scalar.rs
index c251e8bbe..b0f6bd09f 100644
--- a/curve25519-dalek/src/backend/serial/u32/scalar.rs
+++ b/curve25519-dalek/src/backend/serial/u32/scalar.rs
@@ -12,6 +12,7 @@
 
 use core::fmt::Debug;
 use core::ops::{Index, IndexMut};
+use subtle::{Choice, ConditionallySelectable};
 
 #[cfg(feature = "zeroize")]
 use zeroize::Zeroize;
@@ -24,7 +25,7 @@ use crate::constants;
 pub struct Scalar29(pub [u32; 9]);
 
 impl Debug for Scalar29 {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "Scalar29: {:?}", &self.0[..])
     }
 }
@@ -196,10 +197,11 @@ impl Scalar29 {
         }
 
         // conditionally add l if the difference is negative
-        let underflow_mask = ((borrow >> 31) ^ 1).wrapping_sub(1);
         let mut carry: u32 = 0;
         for i in 0..9 {
-            carry = (carry >> 29) + difference[i] + (constants::L[i] & underflow_mask);
+            let underflow = Choice::from((borrow >> 31) as u8);
+            let addend = u32::conditional_select(&0, &constants::L[i], underflow);
+            carry = (carry >> 29) + difference[i] + addend;
             difference[i] = carry & mask;
         }
 
diff --git a/curve25519-dalek/src/backend/serial/u64/field.rs b/curve25519-dalek/src/backend/serial/u64/field.rs
index 9659effa1..1263d23e4 100644
--- a/curve25519-dalek/src/backend/serial/u64/field.rs
+++ b/curve25519-dalek/src/backend/serial/u64/field.rs
@@ -43,7 +43,7 @@ use zeroize::Zeroize;
 pub struct FieldElement51(pub(crate) [u64; 5]);
 
 impl Debug for FieldElement51 {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "FieldElement51({:?})", &self.0[..])
     }
 }
diff --git a/curve25519-dalek/src/backend/serial/u64/scalar.rs b/curve25519-dalek/src/backend/serial/u64/scalar.rs
index dab80cdce..57e2d9b01 100644
--- a/curve25519-dalek/src/backend/serial/u64/scalar.rs
+++ b/curve25519-dalek/src/backend/serial/u64/scalar.rs
@@ -13,6 +13,7 @@
 
 use core::fmt::Debug;
 use core::ops::{Index, IndexMut};
+use subtle::{Choice, ConditionallySelectable};
 
 #[cfg(feature = "zeroize")]
 use zeroize::Zeroize;
@@ -25,7 +26,7 @@ use crate::constants;
 pub struct Scalar52(pub [u64; 5]);
 
 impl Debug for Scalar52 {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "Scalar52: {:?}", &self.0[..])
     }
 }
@@ -185,10 +186,11 @@ impl Scalar52 {
         }
 
         // conditionally add l if the difference is negative
-        let underflow_mask = ((borrow >> 63) ^ 1).wrapping_sub(1);
         let mut carry: u64 = 0;
         for i in 0..5 {
-            carry = (carry >> 52) + difference[i] + (constants::L[i] & underflow_mask);
+            let underflow = Choice::from((borrow >> 63) as u8);
+            let addend = u64::conditional_select(&0, &constants::L[i], underflow);
+            carry = (carry >> 52) + difference[i] + addend;
             difference[i] = carry & mask;
         }
 
diff --git a/curve25519-dalek/src/backend/vector/avx2/edwards.rs b/curve25519-dalek/src/backend/vector/avx2/edwards.rs
index cf6691e83..fd70d7d2f 100644
--- a/curve25519-dalek/src/backend/vector/avx2/edwards.rs
+++ b/curve25519-dalek/src/backend/vector/avx2/edwards.rs
@@ -35,7 +35,6 @@
 
 #![allow(non_snake_case)]
 
-use core::convert::From;
 use core::ops::{Add, Neg, Sub};
 
 use subtle::Choice;
diff --git a/curve25519-dalek/src/backend/vector/ifma/edwards.rs b/curve25519-dalek/src/backend/vector/ifma/edwards.rs
index f8605fe52..3de7030a7 100644
--- a/curve25519-dalek/src/backend/vector/ifma/edwards.rs
+++ b/curve25519-dalek/src/backend/vector/ifma/edwards.rs
@@ -249,7 +249,7 @@ impl<'a> From<&'a edwards::EdwardsPoint> for NafLookupTable8<CachedPoint> {
     }
 }
 
-#[cfg(target_feature = "avx512ifma,avx512vl")]
+#[cfg(all(target_feature = "avx512ifma", target_feature = "avx512vl"))]
 #[cfg(test)]
 mod test {
     use super::*;
diff --git a/curve25519-dalek/src/backend/vector/ifma/field.rs b/curve25519-dalek/src/backend/vector/ifma/field.rs
index fa8ce2dd9..ebdfba1bd 100644
--- a/curve25519-dalek/src/backend/vector/ifma/field.rs
+++ b/curve25519-dalek/src/backend/vector/ifma/field.rs
@@ -629,7 +629,7 @@ impl<'a, 'b> Mul<&'b F51x4Reduced> for &'a F51x4Reduced {
     }
 }
 
-#[cfg(target_feature = "avx512ifma,avx512vl")]
+#[cfg(all(target_feature = "avx512ifma", target_feature = "avx512vl"))]
 #[cfg(test)]
 mod test {
     use super::*;
diff --git a/curve25519-dalek/src/backend/vector/scalar_mul/precomputed_straus.rs b/curve25519-dalek/src/backend/vector/scalar_mul/precomputed_straus.rs
index 5b3bf6726..eb7954e64 100644
--- a/curve25519-dalek/src/backend/vector/scalar_mul/precomputed_straus.rs
+++ b/curve25519-dalek/src/backend/vector/scalar_mul/precomputed_straus.rs
@@ -87,7 +87,7 @@ pub mod spec {
 
             let sp = self.static_lookup_tables.len();
             let dp = dynamic_lookup_tables.len();
-            assert_eq!(sp, static_nafs.len());
+            assert!(sp >= static_nafs.len());
             assert_eq!(dp, dynamic_nafs.len());
 
             // We could save some doublings by looking for the highest
@@ -111,7 +111,7 @@ pub mod spec {
                 }
 
                 #[allow(clippy::needless_range_loop)]
-                for i in 0..sp {
+                for i in 0..static_nafs.len() {
                     let t_ij = static_nafs[i][j];
                     match t_ij.cmp(&0) {
                         Ordering::Greater => {
diff --git a/curve25519-dalek/src/edwards.rs b/curve25519-dalek/src/edwards.rs
index accf22776..53ad4fef7 100644
--- a/curve25519-dalek/src/edwards.rs
+++ b/curve25519-dalek/src/edwards.rs
@@ -19,8 +19,8 @@
 //! ## Equality Testing
 //!
 //! The `EdwardsPoint` struct implements the [`subtle::ConstantTimeEq`]
-//! trait for constant-time equality checking, and the Rust `Eq` trait
-//! for variable-time equality checking.
+//! trait for constant-time equality checking, and also uses this to
+//! ensure `Eq` equality checking runs in constant time.
 //!
 //! ## Cofactor-related functions
 //!
@@ -96,7 +96,6 @@
 use core::array::TryFromSliceError;
 use core::borrow::Borrow;
 use core::fmt::Debug;
-use core::iter::Iterator;
 use core::iter::Sum;
 use core::ops::{Add, Neg, Sub};
 use core::ops::{AddAssign, SubAssign};
@@ -110,10 +109,12 @@ use digest::{generic_array::typenum::U64, Digest};
 #[cfg(feature = "group")]
 use {
     group::{cofactor::CofactorGroup, prime::PrimeGroup, GroupEncoding},
-    rand_core::RngCore,
     subtle::CtOption,
 };
 
+#[cfg(feature = "group")]
+use rand_core::RngCore;
+
 use subtle::Choice;
 use subtle::ConditionallyNegatable;
 use subtle::ConditionallySelectable;
@@ -170,7 +171,7 @@ impl ConstantTimeEq for CompressedEdwardsY {
 }
 
 impl Debug for CompressedEdwardsY {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "CompressedEdwardsY: {:?}", self.as_bytes())
     }
 }
@@ -258,7 +259,7 @@ impl TryFrom<&[u8]> for CompressedEdwardsY {
 #[cfg(feature = "serde")]
 use serde::de::Visitor;
 #[cfg(feature = "serde")]
-use serde::{self, Deserialize, Deserializer, Serialize, Serializer};
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 #[cfg(feature = "serde")]
 impl Serialize for EdwardsPoint {
@@ -301,7 +302,7 @@ impl<'de> Deserialize<'de> for EdwardsPoint {
         impl<'de> Visitor<'de> for EdwardsPointVisitor {
             type Value = EdwardsPoint;
 
-            fn expecting(&self, formatter: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+            fn expecting(&self, formatter: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 formatter.write_str("a valid point in Edwards y + sign format")
             }
 
@@ -337,7 +338,7 @@ impl<'de> Deserialize<'de> for CompressedEdwardsY {
         impl<'de> Visitor<'de> for CompressedEdwardsYVisitor {
             type Value = CompressedEdwardsY;
 
-            fn expecting(&self, formatter: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+            fn expecting(&self, formatter: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 formatter.write_str("32 bytes of data")
             }
 
@@ -437,7 +438,7 @@ impl Zeroize for CompressedEdwardsY {
 
 #[cfg(feature = "zeroize")]
 impl Zeroize for EdwardsPoint {
-    /// Reset this `CompressedEdwardsPoint` to the identity element.
+    /// Reset this `EdwardsPoint` to the identity element.
     fn zeroize(&mut self) {
         self.X.zeroize();
         self.Y = FieldElement::ONE;
@@ -1052,7 +1053,7 @@ macro_rules! impl_basepoint_table {
         }
 
         impl Debug for $name {
-            fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+            fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 write!(f, "{:?}([\n", stringify!($name))?;
                 for i in 0..32 {
                     write!(f, "\t{:?},\n", &self.0[i])?;
@@ -1263,7 +1264,7 @@ impl EdwardsPoint {
 // ------------------------------------------------------------------------
 
 impl Debug for EdwardsPoint {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(
             f,
             "EdwardsPoint{{\n\tX: {:?},\n\tY: {:?},\n\tZ: {:?},\n\tT: {:?}\n}}",
@@ -1334,7 +1335,7 @@ impl GroupEncoding for EdwardsPoint {
 /// A `SubgroupPoint` represents a point on the Edwards form of Curve25519, that is
 /// guaranteed to be in the prime-order subgroup.
 #[cfg(feature = "group")]
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
 pub struct SubgroupPoint(EdwardsPoint);
 
 #[cfg(feature = "group")]
@@ -1509,6 +1510,20 @@ impl MulAssign<&Scalar> for SubgroupPoint {
 #[cfg(feature = "group")]
 define_mul_assign_variants!(LHS = SubgroupPoint, RHS = Scalar);
 
+#[cfg(feature = "group")]
+impl ConstantTimeEq for SubgroupPoint {
+    fn ct_eq(&self, other: &SubgroupPoint) -> Choice {
+        self.0.ct_eq(&other.0)
+    }
+}
+
+#[cfg(feature = "group")]
+impl ConditionallySelectable for SubgroupPoint {
+    fn conditional_select(a: &SubgroupPoint, b: &SubgroupPoint, choice: Choice) -> SubgroupPoint {
+        SubgroupPoint(EdwardsPoint::conditional_select(&a.0, &b.0, choice))
+    }
+}
+
 #[cfg(feature = "group")]
 impl group::Group for SubgroupPoint {
     type Scalar = Scalar;
@@ -1591,8 +1606,10 @@ impl CofactorGroup for EdwardsPoint {
 #[cfg(test)]
 mod test {
     use super::*;
-    use crate::{field::FieldElement, scalar::Scalar};
-    use subtle::ConditionallySelectable;
+
+    // If `group` is set, then this is already imported in super
+    #[cfg(not(feature = "group"))]
+    use rand_core::RngCore;
 
     #[cfg(feature = "alloc")]
     use alloc::vec::Vec;
@@ -1600,8 +1617,6 @@ mod test {
     #[cfg(feature = "precomputed-tables")]
     use crate::constants::ED25519_BASEPOINT_TABLE;
 
-    use rand_core::RngCore;
-
     /// X coordinate of the basepoint.
     /// = 15112221349535400772501151409588531511454012693041857206046113283949847762202
     static BASE_X_COORD_BYTES: [u8; 32] = [
diff --git a/curve25519-dalek/src/field.rs b/curve25519-dalek/src/field.rs
index 87058941e..68c9c8b89 100644
--- a/curve25519-dalek/src/field.rs
+++ b/curve25519-dalek/src/field.rs
@@ -25,8 +25,6 @@
 
 #![allow(unused_qualifications)]
 
-use core::cmp::{Eq, PartialEq};
-
 use cfg_if::cfg_if;
 
 use subtle::Choice;
@@ -310,7 +308,6 @@ impl FieldElement {
 #[cfg(test)]
 mod test {
     use crate::field::*;
-    use subtle::ConditionallyNegatable;
 
     /// Random element a of GF(2^255-19), from Sage
     /// a = 1070314506888354081329385823235218444233221\
diff --git a/curve25519-dalek/src/montgomery.rs b/curve25519-dalek/src/montgomery.rs
index 2be35cdc7..cb5e2fb87 100644
--- a/curve25519-dalek/src/montgomery.rs
+++ b/curve25519-dalek/src/montgomery.rs
@@ -84,6 +84,12 @@ impl ConstantTimeEq for MontgomeryPoint {
     }
 }
 
+impl ConditionallySelectable for MontgomeryPoint {
+    fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
+        Self(<[u8; 32]>::conditional_select(&a.0, &b.0, choice))
+    }
+}
+
 impl PartialEq for MontgomeryPoint {
     fn eq(&self, other: &MontgomeryPoint) -> bool {
         self.ct_eq(other).into()
diff --git a/curve25519-dalek/src/ristretto.rs b/curve25519-dalek/src/ristretto.rs
index dec7ae067..1320bbe48 100644
--- a/curve25519-dalek/src/ristretto.rs
+++ b/curve25519-dalek/src/ristretto.rs
@@ -76,9 +76,9 @@
 //! coordinates without requiring an inversion, so it is much faster.
 //!
 //! The `RistrettoPoint` struct implements the
-//! `subtle::ConstantTimeEq` trait for constant-time equality
-//! checking, and the Rust `Eq` trait for variable-time equality
-//! checking.
+//! [`subtle::ConstantTimeEq`] trait for constant-time equality
+//! checking, and also uses this to ensure `Eq` equality checking
+//! runs in constant time.
 //!
 //! ## Scalars
 //!
@@ -364,7 +364,7 @@ impl TryFrom<&[u8]> for CompressedRistretto {
 #[cfg(feature = "serde")]
 use serde::de::Visitor;
 #[cfg(feature = "serde")]
-use serde::{self, Deserialize, Deserializer, Serialize, Serializer};
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 #[cfg(feature = "serde")]
 impl Serialize for RistrettoPoint {
@@ -407,7 +407,7 @@ impl<'de> Deserialize<'de> for RistrettoPoint {
         impl<'de> Visitor<'de> for RistrettoPointVisitor {
             type Value = RistrettoPoint;
 
-            fn expecting(&self, formatter: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+            fn expecting(&self, formatter: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 formatter.write_str("a valid point in Ristretto format")
             }
 
@@ -443,7 +443,7 @@ impl<'de> Deserialize<'de> for CompressedRistretto {
         impl<'de> Visitor<'de> for CompressedRistrettoVisitor {
             type Value = CompressedRistretto;
 
-            fn expecting(&self, formatter: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+            fn expecting(&self, formatter: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 formatter.write_str("32 bytes of data")
             }
 
@@ -1155,13 +1155,13 @@ impl ConditionallySelectable for RistrettoPoint {
 // ------------------------------------------------------------------------
 
 impl Debug for CompressedRistretto {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "CompressedRistretto: {:?}", self.as_bytes())
     }
 }
 
 impl Debug for RistrettoPoint {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         let coset = self.coset4();
         write!(
             f,
@@ -1277,8 +1277,6 @@ impl Zeroize for RistrettoPoint {
 mod test {
     use super::*;
     use crate::edwards::CompressedEdwardsY;
-    use crate::scalar::Scalar;
-    use crate::traits::Identity;
 
     use rand_core::OsRng;
 
@@ -1871,4 +1869,148 @@ mod test {
         assert_eq!(P.compress(), R.compress());
         assert_eq!(Q.compress(), R.compress());
     }
+
+    #[test]
+    #[cfg(feature = "alloc")]
+    fn partial_precomputed_mixed_multiscalar_empty() {
+        let mut rng = rand::thread_rng();
+
+        let n_static = 16;
+        let n_dynamic = 8;
+
+        let static_points = (0..n_static)
+            .map(|_| RistrettoPoint::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        // Use zero scalars
+        let static_scalars = Vec::new();
+
+        let dynamic_points = (0..n_dynamic)
+            .map(|_| RistrettoPoint::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        let dynamic_scalars = (0..n_dynamic)
+            .map(|_| Scalar::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        // Compute the linear combination using precomputed multiscalar multiplication
+        let precomputation = VartimeRistrettoPrecomputation::new(static_points.iter());
+        let result_multiscalar = precomputation.vartime_mixed_multiscalar_mul(
+            &static_scalars,
+            &dynamic_scalars,
+            &dynamic_points,
+        );
+
+        // Compute the linear combination manually
+        let mut result_manual = RistrettoPoint::identity();
+        for i in 0..static_scalars.len() {
+            result_manual += static_points[i] * static_scalars[i];
+        }
+        for i in 0..n_dynamic {
+            result_manual += dynamic_points[i] * dynamic_scalars[i];
+        }
+
+        assert_eq!(result_multiscalar, result_manual);
+    }
+
+    #[test]
+    #[cfg(feature = "alloc")]
+    fn partial_precomputed_mixed_multiscalar() {
+        let mut rng = rand::thread_rng();
+
+        let n_static = 16;
+        let n_dynamic = 8;
+
+        let static_points = (0..n_static)
+            .map(|_| RistrettoPoint::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        // Use one fewer scalars
+        let static_scalars = (0..n_static - 1)
+            .map(|_| Scalar::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        let dynamic_points = (0..n_dynamic)
+            .map(|_| RistrettoPoint::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        let dynamic_scalars = (0..n_dynamic)
+            .map(|_| Scalar::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        // Compute the linear combination using precomputed multiscalar multiplication
+        let precomputation = VartimeRistrettoPrecomputation::new(static_points.iter());
+        let result_multiscalar = precomputation.vartime_mixed_multiscalar_mul(
+            &static_scalars,
+            &dynamic_scalars,
+            &dynamic_points,
+        );
+
+        // Compute the linear combination manually
+        let mut result_manual = RistrettoPoint::identity();
+        for i in 0..static_scalars.len() {
+            result_manual += static_points[i] * static_scalars[i];
+        }
+        for i in 0..n_dynamic {
+            result_manual += dynamic_points[i] * dynamic_scalars[i];
+        }
+
+        assert_eq!(result_multiscalar, result_manual);
+    }
+
+    #[test]
+    #[cfg(feature = "alloc")]
+    fn partial_precomputed_multiscalar() {
+        let mut rng = rand::thread_rng();
+
+        let n_static = 16;
+
+        let static_points = (0..n_static)
+            .map(|_| RistrettoPoint::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        // Use one fewer scalars
+        let static_scalars = (0..n_static - 1)
+            .map(|_| Scalar::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        // Compute the linear combination using precomputed multiscalar multiplication
+        let precomputation = VartimeRistrettoPrecomputation::new(static_points.iter());
+        let result_multiscalar = precomputation.vartime_multiscalar_mul(&static_scalars);
+
+        // Compute the linear combination manually
+        let mut result_manual = RistrettoPoint::identity();
+        for i in 0..static_scalars.len() {
+            result_manual += static_points[i] * static_scalars[i];
+        }
+
+        assert_eq!(result_multiscalar, result_manual);
+    }
+
+    #[test]
+    #[cfg(feature = "alloc")]
+    fn partial_precomputed_multiscalar_empty() {
+        let mut rng = rand::thread_rng();
+
+        let n_static = 16;
+
+        let static_points = (0..n_static)
+            .map(|_| RistrettoPoint::random(&mut rng))
+            .collect::<Vec<_>>();
+
+        // Use zero scalars
+        let static_scalars = Vec::new();
+
+        // Compute the linear combination using precomputed multiscalar multiplication
+        let precomputation = VartimeRistrettoPrecomputation::new(static_points.iter());
+        let result_multiscalar = precomputation.vartime_multiscalar_mul(&static_scalars);
+
+        // Compute the linear combination manually
+        let mut result_manual = RistrettoPoint::identity();
+        for i in 0..static_scalars.len() {
+            result_manual += static_points[i] * static_scalars[i];
+        }
+
+        assert_eq!(result_multiscalar, result_manual);
+    }
 }
diff --git a/curve25519-dalek/src/scalar.rs b/curve25519-dalek/src/scalar.rs
index 5b9eca1da..6afd74eef 100644
--- a/curve25519-dalek/src/scalar.rs
+++ b/curve25519-dalek/src/scalar.rs
@@ -112,8 +112,6 @@
 //! has been enabled.
 
 use core::borrow::Borrow;
-use core::cmp::{Eq, PartialEq};
-use core::convert::TryInto;
 use core::fmt::Debug;
 use core::iter::{Product, Sum};
 use core::ops::Index;
@@ -124,13 +122,13 @@ use core::ops::{Sub, SubAssign};
 
 use cfg_if::cfg_if;
 
+#[cfg(feature = "group")]
+use group::ff::{Field, FromUniformBytes, PrimeField};
 #[cfg(feature = "group-bits")]
 use group::ff::{FieldBits, PrimeFieldBits};
-#[cfg(feature = "group")]
-use {
-    group::ff::{Field, FromUniformBytes, PrimeField},
-    rand_core::RngCore,
-};
+
+#[cfg(any(test, feature = "group"))]
+use rand_core::RngCore;
 
 #[cfg(any(test, feature = "rand_core"))]
 use rand_core::CryptoRngCore;
@@ -287,7 +285,7 @@ impl Scalar {
 }
 
 impl Debug for Scalar {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "Scalar{{\n\tbytes: {:?},\n}}", &self.bytes)
     }
 }
@@ -402,7 +400,7 @@ impl ConditionallySelectable for Scalar {
 #[cfg(feature = "serde")]
 use serde::de::Visitor;
 #[cfg(feature = "serde")]
-use serde::{self, Deserialize, Deserializer, Serialize, Serializer};
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 #[cfg(feature = "serde")]
 #[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
@@ -432,7 +430,7 @@ impl<'de> Deserialize<'de> for Scalar {
         impl<'de> Visitor<'de> for ScalarVisitor {
             type Value = Scalar;
 
-            fn expecting(&self, formatter: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+            fn expecting(&self, formatter: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 formatter.write_str(
                     "a sequence of 32 bytes whose little-endian interpretation is less than the \
                     basepoint order ℓ",
@@ -833,7 +831,7 @@ impl Scalar {
         }
 
         #[cfg(feature = "zeroize")]
-        zeroize::Zeroize::zeroize(&mut scratch);
+        Zeroize::zeroize(&mut scratch);
 
         ret
     }
@@ -1235,10 +1233,12 @@ impl Field for Scalar {
     }
 
     fn sqrt_ratio(num: &Self, div: &Self) -> (Choice, Self) {
+        #[allow(unused_qualifications)]
         group::ff::helpers::sqrt_ratio_generic(num, div)
     }
 
     fn sqrt(&self) -> CtOption<Self> {
+        #[allow(unused_qualifications)]
         group::ff::helpers::sqrt_tonelli_shanks(
             self,
             [
@@ -1393,13 +1393,10 @@ pub const fn clamp_integer(mut bytes: [u8; 32]) -> [u8; 32] {
 #[cfg(test)]
 pub(crate) mod test {
     use super::*;
-    use crate::constants;
 
     #[cfg(feature = "alloc")]
     use alloc::vec::Vec;
 
-    use rand::RngCore;
-
     /// x = 2238329342913194256032495932344128051776374960164957527413114840482143558222
     pub static X: Scalar = Scalar {
         bytes: [
diff --git a/curve25519-dalek/src/traits.rs b/curve25519-dalek/src/traits.rs
index 870dd32f8..ea7ca3be7 100644
--- a/curve25519-dalek/src/traits.rs
+++ b/curve25519-dalek/src/traits.rs
@@ -15,9 +15,8 @@
 
 use core::borrow::Borrow;
 
-use subtle;
-
 use crate::scalar::{clamp_integer, Scalar};
+use subtle::ConstantTimeEq;
 
 // ------------------------------------------------------------------------
 // Public Traits
@@ -41,7 +40,7 @@ pub trait IsIdentity {
 /// constructor.
 impl<T> IsIdentity for T
 where
-    T: subtle::ConstantTimeEq + Identity,
+    T: ConstantTimeEq + Identity,
 {
     fn is_identity(&self) -> bool {
         self.ct_eq(&T::identity()).into()
@@ -286,7 +285,7 @@ pub trait VartimeMultiscalarMul {
 ///   to be composed into the input iterators.
 ///
 /// All methods require that the lengths of the input iterators be
-/// known and matching, as if they were `ExactSizeIterator`s.  (It
+/// known, as if they were `ExactSizeIterator`s.  (It
 /// does not require `ExactSizeIterator` only because that trait is
 /// broken).
 pub trait VartimePrecomputedMultiscalarMul: Sized {
@@ -307,8 +306,10 @@ pub trait VartimePrecomputedMultiscalarMul: Sized {
     /// $$
     /// where the \\(B_j\\) are the points that were supplied to `new`.
     ///
-    /// It is an error to call this function with iterators of
-    /// inconsistent lengths.
+    /// It is valid for \\(b_i\\) to have a shorter length than \\(B_j\\).
+    /// In this case, any "unused" points are ignored in the computation.
+    /// It is an error to call this function if \\(b_i\\) has a longer
+    /// length than \\(B_j\\).
     ///
     /// The trait bound aims for maximum flexibility: the input must
     /// be convertable to iterators (`I: IntoIter`), and the
@@ -338,8 +339,11 @@ pub trait VartimePrecomputedMultiscalarMul: Sized {
     /// $$
     /// where the \\(B_j\\) are the points that were supplied to `new`.
     ///
-    /// It is an error to call this function with iterators of
-    /// inconsistent lengths.
+    /// It is valid for \\(b_i\\) to have a shorter length than \\(B_j\\).
+    /// In this case, any "unused" points are ignored in the computation.
+    /// It is an error to call this function if \\(b_i\\) has a longer
+    /// length than \\(B_j\\), or if \\(a_i\\) and \\(A_i\\) do not have
+    /// the same length.
     ///
     /// The trait bound aims for maximum flexibility: the inputs must be
     /// convertable to iterators (`I: IntoIter`), and the iterator's items
@@ -379,8 +383,11 @@ pub trait VartimePrecomputedMultiscalarMul: Sized {
     ///
     /// If any of the dynamic points were `None`, return `None`.
     ///
-    /// It is an error to call this function with iterators of
-    /// inconsistent lengths.
+    /// It is valid for \\(b_i\\) to have a shorter length than \\(B_j\\).
+    /// In this case, any "unused" points are ignored in the computation.
+    /// It is an error to call this function if \\(b_i\\) has a longer
+    /// length than \\(B_j\\), or if \\(a_i\\) and \\(A_i\\) do not have
+    /// the same length.
     ///
     /// This function is particularly useful when verifying statements
     /// involving compressed points.  Accepting `Option<Point>` allows
diff --git a/curve25519-dalek/src/window.rs b/curve25519-dalek/src/window.rs
index 8c575ee04..43c4b3abb 100644
--- a/curve25519-dalek/src/window.rs
+++ b/curve25519-dalek/src/window.rs
@@ -83,7 +83,7 @@ macro_rules! impl_lookup_table {
         }
 
         impl<T: Debug> Debug for $name<T> {
-            fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+            fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 write!(f, "{:?}(", stringify!($name))?;
 
                 for x in self.0.iter() {
@@ -193,7 +193,7 @@ impl<T: Copy> NafLookupTable5<T> {
 }
 
 impl<T: Debug> Debug for NafLookupTable5<T> {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "NafLookupTable5({:?})", self.0)
     }
 }
@@ -240,7 +240,7 @@ impl<T: Copy> NafLookupTable8<T> {
 
 #[cfg(any(feature = "precomputed-tables", feature = "alloc"))]
 impl<T: Debug> Debug for NafLookupTable8<T> {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         writeln!(f, "NafLookupTable8([")?;
         for i in 0..64 {
             writeln!(f, "\t{:?},", &self.0[i])?;
diff --git a/ed25519-dalek/src/batch.rs b/ed25519-dalek/src/batch.rs
index ed2618d6c..fa79677d5 100644
--- a/ed25519-dalek/src/batch.rs
+++ b/ed25519-dalek/src/batch.rs
@@ -11,7 +11,6 @@
 
 use alloc::vec::Vec;
 
-use core::convert::TryFrom;
 use core::iter::once;
 
 use curve25519_dalek::constants;
diff --git a/ed25519-dalek/src/lib.rs b/ed25519-dalek/src/lib.rs
index a7cfac488..21d8737ba 100644
--- a/ed25519-dalek/src/lib.rs
+++ b/ed25519-dalek/src/lib.rs
@@ -21,6 +21,7 @@
 #![cfg_attr(feature = "rand_core", doc = "```")]
 #![cfg_attr(not(feature = "rand_core"), doc = "```ignore")]
 //! # fn main() {
+//! // $ cargo add ed25519_dalek --features rand_core
 //! use rand::rngs::OsRng;
 //! use ed25519_dalek::SigningKey;
 //! use ed25519_dalek::Signature;
diff --git a/ed25519-dalek/src/signature.rs b/ed25519-dalek/src/signature.rs
index 36174c8d6..af8276834 100644
--- a/ed25519-dalek/src/signature.rs
+++ b/ed25519-dalek/src/signature.rs
@@ -9,7 +9,6 @@
 
 //! An ed25519 signature.
 
-use core::convert::TryFrom;
 use core::fmt::Debug;
 
 use curve25519_dalek::edwards::CompressedEdwardsY;
@@ -58,7 +57,7 @@ impl Clone for InternalSignature {
 }
 
 impl Debug for InternalSignature {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "Signature( R: {:?}, s: {:?} )", &self.R, &self.s)
     }
 }
diff --git a/ed25519-dalek/src/signing.rs b/ed25519-dalek/src/signing.rs
index e2818fea7..8999f50d2 100644
--- a/ed25519-dalek/src/signing.rs
+++ b/ed25519-dalek/src/signing.rs
@@ -131,7 +131,7 @@ impl SigningKey {
     /// # Returns
     ///
     /// A `Result` whose okay value is an EdDSA [`SigningKey`] or whose error value
-    /// is an `SignatureError` describing the error that occurred.
+    /// is a `SignatureError` describing the error that occurred.
     #[inline]
     pub fn from_keypair_bytes(bytes: &[u8; 64]) -> Result<SigningKey, SignatureError> {
         let (secret_key, verifying_key) = bytes.split_at(SECRET_KEY_LENGTH);
@@ -543,7 +543,7 @@ impl AsRef<VerifyingKey> for SigningKey {
 }
 
 impl Debug for SigningKey {
-    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         f.debug_struct("SigningKey")
             .field("verifying_key", &self.verifying_key)
             .finish_non_exhaustive() // avoids printing `secret_key`
@@ -742,7 +742,7 @@ impl<'d> Deserialize<'d> for SigningKey {
         impl<'de> serde::de::Visitor<'de> for SigningKeyVisitor {
             type Value = SigningKey;
 
-            fn expecting(&self, formatter: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+            fn expecting(&self, formatter: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 write!(formatter, concat!("An ed25519 signing (private) key"))
             }
 
diff --git a/ed25519-dalek/src/verifying.rs b/ed25519-dalek/src/verifying.rs
index b53032144..246951b44 100644
--- a/ed25519-dalek/src/verifying.rs
+++ b/ed25519-dalek/src/verifying.rs
@@ -9,7 +9,6 @@
 
 //! ed25519 public keys.
 
-use core::convert::TryFrom;
 use core::fmt::Debug;
 use core::hash::{Hash, Hasher};
 
@@ -643,7 +642,7 @@ impl<'d> Deserialize<'d> for VerifyingKey {
         impl<'de> serde::de::Visitor<'de> for VerifyingKeyVisitor {
             type Value = VerifyingKey;
 
-            fn expecting(&self, formatter: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
+            fn expecting(&self, formatter: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                 write!(formatter, concat!("An ed25519 verifying (public) key"))
             }
 
diff --git a/ed25519-dalek/tests/ed25519.rs b/ed25519-dalek/tests/ed25519.rs
index 82ac33d76..edab8a814 100644
--- a/ed25519-dalek/tests/ed25519.rs
+++ b/ed25519-dalek/tests/ed25519.rs
@@ -27,10 +27,11 @@ mod vectors {
         scalar::Scalar,
         traits::IsIdentity,
     };
+
+    #[cfg(not(feature = "digest"))]
     use sha2::{digest::Digest, Sha512};
 
     use std::{
-        convert::TryFrom,
         fs::File,
         io::{BufRead, BufReader},
         ops::Neg,
@@ -288,8 +289,6 @@ mod vectors {
 mod integrations {
     use super::*;
     use rand::rngs::OsRng;
-    #[cfg(feature = "digest")]
-    use sha2::Sha512;
     use std::collections::HashMap;
 
     #[test]
diff --git a/x25519-dalek/src/lib.rs b/x25519-dalek/src/lib.rs
index 9a5fc1938..7886eeaa5 100644
--- a/x25519-dalek/src/lib.rs
+++ b/x25519-dalek/src/lib.rs
@@ -15,7 +15,6 @@
 // README.md as the crate documentation.
 
 #![no_std]
-#![cfg_attr(feature = "bench", feature(test))]
 #![cfg_attr(docsrs, feature(doc_auto_cfg, doc_cfg, doc_cfg_hide))]
 #![cfg_attr(docsrs, doc(cfg_hide(docsrs)))]
 #![deny(missing_docs)]