--- a/check	Wed May 26 00:33:35 2010 +0200
+++ b/check	Sat Jun 05 22:25:22 2010 +0200
@@ -103,7 +103,7 @@
 
             print "* DIFFERS *\n";
 
-            $_ = join " ", "diff", "-u",
+            $_ = join " " => "diff", "-u",
               "--label=got",
               "--label=expected",
               $tmp_result->filename,