diff --git a/pipe-gui/src/main/java/pipe/gui/widgets/TransitionFunctionEditor.java b/pipe-gui/src/main/java/pipe/gui/widgets/TransitionFunctionEditor.java
index df027dba..a91f4eb9 100644
--- a/pipe-gui/src/main/java/pipe/gui/widgets/TransitionFunctionEditor.java
+++ b/pipe-gui/src/main/java/pipe/gui/widgets/TransitionFunctionEditor.java
@@ -33,7 +33,7 @@ public TransitionFunctionEditor(TransitionEditorPanel transitionEditorPanel,
         init(petriNet);
     }
 
-    private void init(PetriNet petriNet) {
+    private void init(final PetriNet petriNet) {
 
         final JTextArea function = new JTextArea();
         function.setText(transitionController.getRateExpr());
@@ -80,8 +80,7 @@ public void actionPerformed(java.awt.event.ActionEvent evt) {
                         exit();
                         return;
                     }
-                    //TODD: DONT PASS NULL
-                    ExprEvaluator parser = new ExprEvaluator(null);
+                    ExprEvaluator parser = new ExprEvaluator(petriNet);
                     if (parser.parseAndEvalExprForTransition(func) != null) {
                         _editor.setRate(func);
                         //transitionController.setRate(func);