diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 5b4bfb9..e0c3bc2 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -65,7 +65,7 @@ enum migratetype {
 };
 
 /* In mm/page_alloc.c; keep in sync also with show_migration_types() there */
-extern char * const migratetype_names[MIGRATE_TYPES];
+extern const char * const migratetype_names[MIGRATE_TYPES];
 
 #ifdef CONFIG_CMA
 #  define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA)