diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4f95bcf..59153da 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1525,7 +1525,7 @@
 	long min = mark;
 	int o;
 
-	free_pages -= (1 << order) + 1;
+	free_pages -= (1 << order) - 1;
 	if (alloc_flags & ALLOC_HIGH)
 		min -= min / 2;
 	if (alloc_flags & ALLOC_HARDER)