diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4f59d90b81e65a314e0433dc61371b785b3df61f..b5468de49869d51140bf77123663a16c4191ade4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -900,7 +900,8 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 		      int classzone_idx, int alloc_flags)
 {
 	/* free_pages my go negative - that's OK */
-	long min = mark, free_pages = z->free_pages - (1 << order) + 1;
+	unsigned long min = mark;
+	long free_pages = z->free_pages - (1 << order) + 1;
 	int o;
 
 	if (alloc_flags & ALLOC_HIGH)