diff --git a/src/c/alloc_2.d b/src/c/alloc_2.d
index 79e097781..957d48b1d 100755
--- a/src/c/alloc_2.d
+++ b/src/c/alloc_2.d
@@ -25,6 +25,10 @@
 #include <winsock.h>
 #endif
 
+#ifndef __GCC__
+# define __builtin_expect(form,value) (form)
+#endif
+
 #ifdef GBC_BOEHM
 
 static void finalize_queued();