diff --git a/kernel/memremap.c b/kernel/memremap.c
index 0612323..426547a 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -245,7 +245,8 @@
 
 	/* pages are dead and unused, undo the arch mapping */
 	align_start = res->start & ~(SECTION_SIZE - 1);
-	align_size = ALIGN(resource_size(res), SECTION_SIZE);
+	align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
+		- align_start;
 
 	lock_device_hotplug();
 	mem_hotplug_begin();