diff --git a/SyntaxHighlight_GeSHi.class.php b/SyntaxHighlight_GeSHi.class.php
index 632c85d8..c413f534 100644
--- a/SyntaxHighlight_GeSHi.class.php
+++ b/SyntaxHighlight_GeSHi.class.php
@@ -287,6 +287,19 @@ class SyntaxHighlight_GeSHi {
 	 * @return string
 	 */
 	public static function buildHeadItem( $geshi ) {
+		/**
+		 * Geshi comes by default with a font-family set to monospace which
+		 * ends ultimately ends up causing the font-size to be smaller than
+		 * one would expect (causing bug 26204).
+		 * We append to the default geshi style a CSS hack which is to specify
+		 * monospace twice which "reset" the browser font-size specified for monospace.
+		 *
+		 * The hack is documented in MediaWiki core under
+		 * docs/uidesign/monospace.html and in bug 33496.
+		 */
+		$geshi->set_code_style( 'font-family: monospace, monospace;',
+			/** preserve defaults */ true );
+
 		$lang = $geshi->language;
 		$css = array();
 		$css[] = '<style type="text/css">/*<![CDATA[*/';