Index: parsing_c/compare_c.ml
--- parsing_c/compare_c.ml.orig
+++ parsing_c/compare_c.ml
@@ -211,9 +211,9 @@ let is_normal_space_or_comment to_expected = function
 let get_diff filename1 filename2 bs =
   let com =
     match !Flag_parsing_c.diff_lines with
-      None -> Printf.sprintf "diff -u %s %s %s" bs filename1 filename2
+      None -> Printf.sprintf "gdiff -u %s %s %s" bs filename1 filename2
     | Some n ->
-	Printf.sprintf "diff -U %s %s %s %s" n bs filename1 filename2 in
+	Printf.sprintf "gdiff -U %s %s %s %s" n bs filename1 filename2 in
   let xs = Common.cmd_to_list com in
 
   (* get rid of the --- and +++ lines *)
