diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index f484b93..5e139fe 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -165,8 +165,8 @@
 	unsigned long undo_pfn;
 	struct page *page;
 
-	BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
-	BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
+	BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
+	BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
 
 	for (pfn = start_pfn;
 	     pfn < end_pfn;