diff --git a/src/undo.c b/src/undo.c
index d01ca9b..ec06f31 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -1535,6 +1535,7 @@
 	/* For systems that support ACL: get the ACL from the original file. */
 	acl = mch_get_acl(buf->b_ffname);
 	mch_set_acl(file_name, acl);
+	mch_free_acl(acl);
     }
 #endif