diff --git a/include/msvcrt/stddef.h b/include/msvcrt/stddef.h
index 0ceb65d91cd..cc38d569177 100644
--- a/include/msvcrt/stddef.h
+++ b/include/msvcrt/stddef.h
@@ -28,7 +28,9 @@
 #endif
 #endif
 
-#ifdef _WIN64
+#ifdef __GNUC__
+#define offsetof(s,m)       __builtin_offsetof(s,m)
+#elif defined(_WIN64)
 #define offsetof(s,m)       (size_t)((ptrdiff_t)&(((s*)NULL)->m))
 #else
 #define offsetof(s,m)       (size_t)&(((s*)NULL)->m)