diff --git a/utils/src/util.h b/utils/src/util.h
index 2fafc0e9..da751caf 100644
--- a/utils/src/util.h
+++ b/utils/src/util.h
@@ -82,6 +82,7 @@ do {				\
 							\
 	(_x == 0 ? 0 : 64 - __builtin_clzll(_x));	\
 })
+#define fls64(x) flsll(x)
 
 #define ilog2(x)					\
 ({							\