diff --git a/docsrc/content/extensions.fsx b/docsrc/content/extensions.fsx
index bb38da66a..6ed266d50 100644
--- a/docsrc/content/extensions.fsx
+++ b/docsrc/content/extensions.fsx
@@ -186,6 +186,7 @@ The String type:
    * truncate, drop
    * findIndex, tryFindIndex
    * findSliceIndex, tryFindSliceIndex
+   * findLastSliceIndex, tryFindLastSliceIndex
    * toArray, ofArray, toList, ofList, toSeq, ofSeq, toCodePoints, ofCodePoints
    * getBytes
 
@@ -195,6 +196,7 @@ Collections / Traversable types:
    * intercalate, intersperse,
    * split, replace,
    * findSliceIndex, trySliceIndex,
+   * findLastSliceIndex, tryLastSliceIndex,
    * partitionMap
  * [IList](reference/fsharpplus-ilist.html)
    * toIReadOnlyList
@@ -207,6 +209,7 @@ Collections / Traversable types:
    * split, replace,
    * toIReadOnlyList,
    * findSliceIndex, tryFindSliceIndex,
+   * findLastSliceIndex, tryLastSliceIndex,
    * partitionMap
    * setAt, removeAt
  * [Enumerator](reference/fsharpplus-enumerator.html)
@@ -232,6 +235,7 @@ Collections / Traversable types:
     * replicate
     * toIReadOnlyList
     * findSliceIndex, tryFindSliceIndex
+    * findLastSliceIndex, tryLastSliceIndex,
  * [ IReadOnlyCollection ](reference/fsharpplus-ireadonlycollection.html)
      * ofArray, ofList, ofSeq
      * map
diff --git a/src/FSharpPlus/Internals.fs b/src/FSharpPlus/Internals.fs
index ec38039d4..deb064df8 100644
--- a/src/FSharpPlus/Internals.fs
+++ b/src/FSharpPlus/Internals.fs
@@ -429,7 +429,7 @@ module FindLastSliceIndex =
         // we assume the slice is finite (otherwise it cannot be searched)
         let slice = slice |> Seq.toArray
         use sourceEnumerator = source.GetEnumerator()
-        // we also assume either the source is finite
+        // we also assume the source is finite
         let rec go last index =
             if sourceEnumerator.MoveNext() then
                 cache.Enqueue sourceEnumerator.Current
@@ -503,7 +503,7 @@ module FindLastSliceIndex =
                 let h = source.[index]
                 cache.Enqueue h
                 if cache.Count = slice.Length then
-                    if sequenceEqual cache revSlice then index - slice.Length + 1
+                    if sequenceEqual cache revSlice then index
                     else
                         cache.Dequeue() |> ignore
                         go (index - 1)
diff --git a/tests/FSharpPlus.Tests/General.fs b/tests/FSharpPlus.Tests/General.fs
index 4b9b2f7a3..ef124e1b5 100644
--- a/tests/FSharpPlus.Tests/General.fs
+++ b/tests/FSharpPlus.Tests/General.fs
@@ -112,15 +112,12 @@ type WrappedListD<'s> = WrappedListD of 's list with
         WrappedListD <!> (traversei f x : ^r)
     static member FindIndex (WrappedListD x, y) =
         SideEffects.add "Using WrappedListD's FindIndex"
-        printfn "WrappedListD.FindIndex"
         findIndex y x
     static member FindSliceIndex (WrappedListD x, WrappedListD y) =
         SideEffects.add "Using WrappedListD's FindSliceIndex"
-        printfn "WrappedListD.FindSliceIndex"
         findSliceIndex y x
     static member FindLastSliceIndex (WrappedListD x, WrappedListD y) =
         SideEffects.add "Using WrappedListD's FindLastSliceIndex"
-        printfn "WrappedListD.FindLastSliceIndex"
         findLastSliceIndex y x
     member this.Length =
         SideEffects.add "Using WrappedListD's Length"
diff --git a/tests/FSharpPlusFable.Tests/FSharpTests/General/Util.fs b/tests/FSharpPlusFable.Tests/FSharpTests/General/Util.fs
index a12f4f4ea..711a12071 100644
--- a/tests/FSharpPlusFable.Tests/FSharpTests/General/Util.fs
+++ b/tests/FSharpPlusFable.Tests/FSharpTests/General/Util.fs
@@ -103,12 +103,13 @@ type WrappedListD<'s> = WrappedListD of 's list with
         WrappedListD <!> (traversei f x : ^r)
     static member FindIndex (WrappedListD x, y) =
         SideEffects.add "Using WrappedListD's FindIndex"
-        printfn "WrappedListD.FindIndex"
         findIndex y x
     static member FindSliceIndex (WrappedListD x, WrappedListD y) =
         SideEffects.add "Using WrappedListD's FindSliceIndex"
-        printfn "WrappedListD.FindSliceIndex"
         findSliceIndex y x
+    static member FindLastSliceIndex (WrappedListD x, WrappedListD y) =
+        SideEffects.add "Using WrappedListD's FindLastSliceIndex"
+        findLastSliceIndex y x
     member this.Length =
         SideEffects.add "Using WrappedListD's Length"
         let (WrappedListD lst) = this