diff --git a/mingw-w64-tools/widl/include/winnt.h b/mingw-w64-tools/widl/include/winnt.h
index 14cfe64af..e2971ba2b 100644
--- a/mingw-w64-tools/widl/include/winnt.h
+++ b/mingw-w64-tools/widl/include/winnt.h
@@ -6768,6 +6768,7 @@ static FORCEINLINE void WriteNoFence( LONG volatile *dest, LONG value )
     __WINE_ATOMIC_STORE_RELAXED( dest, &value );
 }
 
+#if !defined(__MINGW_FASTFAIL_IMPL)
 static FORCEINLINE DECLSPEC_NORETURN void __fastfail(unsigned int code)
 {
 #if defined(__x86_64__) || defined(__i386__)
@@ -6780,6 +6781,7 @@ static FORCEINLINE DECLSPEC_NORETURN void __fastfail(unsigned int code)
     for (;;) __asm__ __volatile__( "udf #0xfb" :: "r" (val) : "memory" );
 #endif
 }
+#endif
 
 #endif  /* __GNUC__ */