diff --git a/include/common/ebtree.h b/include/common/ebtree.h
index 5ef965b..b737bc9 100644
--- a/include/common/ebtree.h
+++ b/include/common/ebtree.h
@@ -329,7 +329,7 @@
  * only work with ints and booleans though.
  */
 #define likely(x) (x)
-#define unlikely(x) (__builtin_expect((x), 0))
+#define unlikely(x) (__builtin_expect((unsigned long)(x), 0))
 #endif
 #endif