diff --git a/contrib/mergetools.hgrc b/contrib/mergetools.hgrc
--- a/contrib/mergetools.hgrc
+++ b/contrib/mergetools.hgrc
@@ -16,6 +16,7 @@ gvimdiff.regname=path
 gvimdiff.priority=-9
 
 vimdiff.args=$local $other $base
+vimdiff.check=changed
 vimdiff.priority=-10
 
 merge.checkconflicts=True