--- a/tests/test-extension.t	Thu Mar 08 13:35:27 2012 -0600
+++ b/tests/test-extension.t	Mon Mar 12 09:39:30 2012 +0100
@@ -301,7 +301,8 @@
     # (see http://www.vim.org/scripts/script.php?script_id=102) Non
     # English user, be sure to put "let g:DirDiffDynamicDiffText = 1" in
     # your .vimrc
-    vimdiff = gvim -f '+next' '+execute "DirDiff" argv(0) argv(1)'
+    vimdiff = gvim -f "+next" \
+              "+execute 'DirDiff' fnameescape(argv(0)) fnameescape(argv(1))"
   
   Tool arguments can include variables that are expanded at runtime: