diff --git a/common_mips.h b/common_mips.h
index 5a2881415..bb579d166 100644
--- a/common_mips.h
+++ b/common_mips.h
@@ -33,8 +33,8 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef COMMON_MIPS
 #define COMMON_MIPS
 
-#define MB
-#define WMB
+#define MB  __sync_synchronize()
+#define WMB __sync_synchronize()
 
 #define INLINE inline
 
diff --git a/common_mips64.h b/common_mips64.h
index 6078bf35b..21e706ca3 100644
--- a/common_mips64.h
+++ b/common_mips64.h
@@ -71,8 +71,8 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef COMMON_MIPS64
 #define COMMON_MIPS64
 
-#define MB
-#define WMB
+#define MB  __sync_synchronize()
+#define WMB __sync_synchronize()
 
 #define INLINE inline