diff --git a/fuzz/fuzz_targets/asm.rs b/fuzz/fuzz_targets/asm.rs
index dbadc87a..7f528bf4 100644
--- a/fuzz/fuzz_targets/asm.rs
+++ b/fuzz/fuzz_targets/asm.rs
@@ -2,21 +2,24 @@
 use ckb_vm::cost_model::constant_cycles;
 use ckb_vm::machine::asm::{AsmCoreMachine, AsmMachine};
 use ckb_vm::machine::{DefaultMachineBuilder, VERSION2};
-use ckb_vm::{Bytes, ISA_A, ISA_B, ISA_IMC, ISA_MOP};
+use ckb_vm::{Bytes, Error, ISA_A, ISA_B, ISA_IMC, ISA_MOP};
 use libfuzzer_sys::fuzz_target;
 
-fn run(data: &[u8]) {
+fn run(data: &[u8]) -> Result<i8, Error> {
     let asm_core = AsmCoreMachine::new(ISA_IMC | ISA_A | ISA_B | ISA_MOP, VERSION2, 200_000);
     let core = DefaultMachineBuilder::<Box<AsmCoreMachine>>::new(asm_core)
         .instruction_cycle_func(Box::new(constant_cycles))
         .build();
     let mut machine = AsmMachine::new(core);
     let program = Bytes::copy_from_slice(data);
-    if let Ok(_) = machine.load_program(&program, &[]) {
-        let _ = machine.run();
-    }
+    machine.load_program(&program, &[])?;
+    machine.run()
 }
 
 fuzz_target!(|data: &[u8]| {
-    run(data);
+    let r0 = run(data);
+    let r1 = run(data);
+    let r2 = run(data);
+    assert_eq!(r0, r1);
+    assert_eq!(r1, r2);
 });
diff --git a/fuzz/fuzz_targets/interpreter.rs b/fuzz/fuzz_targets/interpreter.rs
index b19f2bf8..683c344a 100644
--- a/fuzz/fuzz_targets/interpreter.rs
+++ b/fuzz/fuzz_targets/interpreter.rs
@@ -3,10 +3,10 @@ use ckb_vm::cost_model::constant_cycles;
 use ckb_vm::machine::{DefaultCoreMachine, DefaultMachineBuilder, VERSION2};
 use ckb_vm::memory::sparse::SparseMemory;
 use ckb_vm::memory::wxorx::WXorXMemory;
-use ckb_vm::{Bytes, ISA_A, ISA_B, ISA_IMC, ISA_MOP};
+use ckb_vm::{Bytes, Error, ISA_A, ISA_B, ISA_IMC, ISA_MOP};
 use libfuzzer_sys::fuzz_target;
 
-fn run(data: &[u8]) {
+fn run(data: &[u8]) -> Result<i8, Error> {
     let machine_core = DefaultCoreMachine::<u64, WXorXMemory<SparseMemory<u64>>>::new(
         ISA_IMC | ISA_A | ISA_B | ISA_MOP,
         VERSION2,
@@ -16,11 +16,14 @@ fn run(data: &[u8]) {
         .instruction_cycle_func(Box::new(constant_cycles))
         .build();
     let program = Bytes::copy_from_slice(data);
-    if let Ok(_) = machine.load_program(&program, &[]) {
-        let _ = machine.run();
-    }
+    machine.load_program(&program, &[])?;
+    machine.run()
 }
 
 fuzz_target!(|data: &[u8]| {
-    run(data);
+    let r0 = run(data);
+    let r1 = run(data);
+    let r2 = run(data);
+    assert_eq!(r0, r1);
+    assert_eq!(r1, r2);
 });