diff --git a/syntax.php b/syntax.php
index 23963bd..4daa63f 100755
--- a/syntax.php
+++ b/syntax.php
@@ -48,7 +48,7 @@ public function connectTo($mode) {
     /**
      * Read the information from the matched wiki text
      */
-    public function handle($match, $state, $pos, &$handler){
+    public function handle($match, $state, $pos, Doku_Handler $handler){
         $stripped = substr($match, 2); // Remove initial 'SW'
         $splitted = preg_split("/[pP]/", $stripped); // Split '1613p8' into '1613' and '8'.
         list($wafer, $chip) = $splitted;
@@ -59,7 +59,7 @@ public function handle($match, $state, $pos, &$handler){
     /**
      * Generate HTML output
      */
-    public function render($mode, &$renderer, $data) {
+    public function render($mode, Doku_Renderer $renderer, $data) {
         if($mode != 'xhtml'){
             return false;
         }