diff --git a/src/FSharpPlus/Extensions/String.fs b/src/FSharpPlus/Extensions/String.fs
index 4b5dc5e09..85cb83b53 100644
--- a/src/FSharpPlus/Extensions/String.fs
+++ b/src/FSharpPlus/Extensions/String.fs
@@ -52,6 +52,7 @@ module String =
         
         source.Contains subString
 
+    #if !FABLE_COMPILER_3
     /// Does the source string start with the given subString? -- function wrapper for String.StartsWith method using InvariantCulture.
     let startsWith (subString: string) (source: string) =
         #if !NET45
@@ -60,6 +61,7 @@ module String =
         #endif
         
         source.StartsWith (subString, false, CultureInfo.InvariantCulture)
+    #endif
 
     /// Does the source string end with the given subString? -- function wrapper for String.EndsWith method using InvariantCulture.
     let endsWith subString (source: string) =