--- a/hgext/extdiff.py	Thu Mar 08 13:35:27 2012 -0600
+++ b/hgext/extdiff.py	Mon Mar 12 09:39:30 2012 +0100
@@ -33,7 +33,8 @@
   # (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::