diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a2acaf820fe5..9ca1d604f7cd 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -375,7 +375,7 @@ void online_page(struct page *page)
 #endif
 
 #ifdef CONFIG_FLATMEM
-	max_mapnr = max(page_to_pfn(page), max_mapnr);
+	max_mapnr = max(pfn, max_mapnr);
 #endif
 
 	ClearPageReserved(page);