diff --git a/mingw-w64-headers/crt/_mingw.h.in b/mingw-w64-headers/crt/_mingw.h.in
index f931579a7..5a36facd3 100644
--- a/mingw-w64-headers/crt/_mingw.h.in
+++ b/mingw-w64-headers/crt/_mingw.h.in
@@ -612,6 +612,7 @@ __MINGW_INTRIN_INLINE void __cdecl __MINGW_ATTRIB_NORETURN __fastfail(unsigned i
 #else
   __asm__ __volatile__("unimplemented");
 #endif
+  __builtin_unreachable();
 }
 #endif /* __MINGW_FASTFAIL_IMPL == 1 */