diff --git a/src/undo.c b/src/undo.c
index ec7b1a4..af91bd3 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -3304,7 +3304,7 @@
 #ifdef FEAT_QUICKFIX
 	    !bt_dontwrite(buf) &&
 #endif
-	    (buf->b_changed || file_ff_differs(buf));
+	    (buf->b_changed || file_ff_differs(buf, TRUE));
 }
 
     int
@@ -3314,7 +3314,7 @@
 #ifdef FEAT_QUICKFIX
 	!bt_dontwrite(curbuf) &&
 #endif
-	(curbuf->b_changed || file_ff_differs(curbuf));
+	(curbuf->b_changed || file_ff_differs(curbuf, TRUE));
 }
 
 #if defined(FEAT_EVAL) || defined(PROTO)