updated for version 7.2-133
diff --git a/src/diff.c b/src/diff.c
index c20d095..34e78b6 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -1153,7 +1153,7 @@
 
     for (wp = firstwin; wp != NULL; wp = wp->w_next)
     {
-	if (wp == curwin || eap->forceit)
+	if (wp == curwin || (eap->forceit && wp->w_p_diff))
 	{
 	    /* Set 'diff', 'scrollbind' off and 'wrap' on. */
 	    wp->w_p_diff = FALSE;