diff --git a/lib/bit.h b/lib/bit.h
index 9ffe2060..076e01a0 100644
--- a/lib/bit.h
+++ b/lib/bit.h
@@ -41,7 +41,7 @@ bit_ceil_wrapul(unsigned long x)
 inline int
 leading_zerosul(unsigned long x)
 {
-	return (x == 0) ? ULONG_WIDTH : __builtin_clz(x);
+	return (x == 0) ? ULONG_WIDTH : __builtin_clzl(x);
 }