diff --git a/trunk/functions.pl b/trunk/functions.pl
index 46a1e96..4e45e90 100644
--- a/trunk/functions.pl
+++ b/trunk/functions.pl
@@ -301,9 +301,8 @@ sub output_page
 
     # let the XSLT param choose other stylesheets or default to xhtml.xsl
     my $param_xslt = $query->param('xslt');
-    
-    $param_xslt =~ s/[^a-z0-9\$\-_.+!*'(),]//gi;
-    
+    $param_xslt =~ s/[^a-z0-9\[\]\$\-_.+!*'(),]//gi;
+
     if( -f "$root/xsl/$param_xslt.xsl")
     {
         $xsltpath = "$root/xsl/$param_xslt.xsl"