diff --git a/common_x86.h b/common_x86.h
index 99adc9f5b..ec928e236 100644
--- a/common_x86.h
+++ b/common_x86.h
@@ -47,6 +47,7 @@
 
 #define MB
 #define WMB
+#define RMB
 
 #ifdef C_SUN
 #define	__asm__ __asm