diff --git a/malloc/malloc.c b/malloc/malloc.c
index 645bcbe2dd..f674f4ebfe 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -1317,11 +1317,11 @@ static void      free_atfork();
 
 /* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
 
-#define PREV_INUSE 0x1
+#define PREV_INUSE 0x1UL
 
 /* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
 
-#define IS_MMAPPED 0x2
+#define IS_MMAPPED 0x2UL
 
 /* Bits to mask off when extracting size */