Index: SyntaxHighlight_GeSHi.php
===================================================================
--- SyntaxHighlight_GeSHi.php   (revision 103698)
+++ SyntaxHighlight_GeSHi.php   (working copy)
@@ -58,6 +58,7 @@
 if ( version_compare( $wgVersion, '1.17alpha', '>=' ) ) {
        // For MediaWiki 1.17 alpha and later.
        $wgHooks['ExtensionTypes'][] = 'SyntaxHighlight_GeSHi::hSpecialVersion_GeSHi';
+       $wgAutoloadClasses['HighlightGeSHiLocal']               = $dir . 'SyntaxHighlightGeSHi.local.php';
 } else {
        // For pre-MediaWiki 1.17 alpha.
        $wgHooks['SpecialVersionExtensionTypes'][] = 'SyntaxHighlight_GeSHi::hOldSpecialVersion_GeSHi';
Index: SyntaxHighlight_GeSHi.local.php
===================================================================
--- SyntaxHighlight_GeSHi.local.php     (revision 0)
+++ SyntaxHighlight_GeSHi.local.php     (revision 0)
@@ -0,0 +1,16 @@
+<?php
+/**
+ * Custom ResourceLoader module that loads a Geshi.css per-wiki.
+ */
+class HighlightGeSHilocal extends ResourceLoaderWikiModule {
+
+       /**
+        * @param $context ResourceLoaderContext
+        * @return array
+        */
+       protected function getPages( ResourceLoaderContext $context ) {
+               return array(
+                       'MediaWiki:Geshi.css'      => array( 'type' => 'text' ),
+               );
+       }
+}