diff --git a/Command/DiffDriver.hs b/Command/DiffDriver.hs
index 5bac213975..4c0e8b7fbc 100644
--- a/Command/DiffDriver.hs
+++ b/Command/DiffDriver.hs
@@ -106,9 +106,13 @@ parseReq opts
 fixupReq :: Req -> Options -> Annex Req
 fixupReq req@(UnmergedReq {}) _ = return req
 fixupReq req@(Req {}) opts = 
-	check rOldFile rOldMode (\r f -> r { rOldFile = f }) req
-		>>= check rNewFile rNewMode (\r f -> r { rNewFile = f })
+	check rOldFile rOldMode setoldfile req
+		>>= check rNewFile rNewMode setnewfile
   where
+	setoldfile r@(Req {}) f = r { rOldFile = f }
+	setoldfile r@(UnmergedReq {}) _ = r
+	setnewfile r@(Req {}) f = r { rNewFile = f }
+	setnewfile r@(UnmergedReq {}) _ = r
 	check getfile getmode setfile r = case readTreeItemType (encodeBS (getmode r)) of
 		Just TreeSymlink -> do
 			v <- getAnnexLinkTarget' f False