diff --git a/mingw-w64-headers/ddk/include/ddk/wdm.h b/mingw-w64-headers/ddk/include/ddk/wdm.h
index 6ac1690..f54e0a1 100644
--- a/mingw-w64-headers/ddk/include/ddk/wdm.h
+++ b/mingw-w64-headers/ddk/include/ddk/wdm.h
@@ -369,19 +369,6 @@
 
 #endif // _M_AMD64
 
-#if defined(_M_AMD64) && !defined(RC_INVOKED) && !defined(MIDL_PASS)
-//#if !defined(_X86AMD64_) // FIXME: what's _X86AMD64_ used for?
-FORCEINLINE
-LONG64
-InterlockedAdd64(
-  IN OUT LONG64 volatile *Addend,
-  IN LONG64 Value)
-{
-  return InterlockedExchangeAdd64(Addend, Value) + Value;
-}
-//#endif
-#endif
-
 #endif /* !__INTERLOCKED_DECLARED */