diff --git a/ikiwiki.setup b/ikiwiki.setup
index ab06a7644d..9687389c6f 100644
--- a/ikiwiki.setup
+++ b/ikiwiki.setup
@@ -144,6 +144,7 @@ timezone: GMT
 #exclude: ^(*\.private|Makefile)$
 # specifies the characters that are allowed in source filenames
 wiki_file_chars: -[:alnum:]+/._
+wiki_file_regexp: (^[$config{wiki_file_chars}]+[:alnum:]$)
 # allow symlinks in the path leading to the srcdir (potentially insecure)
 allow_symlinks_before_srcdir: 0
 # cookie control