diff --git a/src/renderable/colorlayer.js b/src/renderable/colorlayer.js
index <HASH>..<HASH> 100644
--- a/src/renderable/colorlayer.js
+++ b/src/renderable/colorlayer.js
@@ -12,7 +12,7 @@ import Renderable from "./renderable.js";
  * @constructor
  * @param {String} name Layer name
  * @param {me.Color|String} color CSS color
- * @param {Number} z z-index position
+ * @param {Number} [z = 0] z-index position
  */
 class ColorLayer extends Renderable {
 
@@ -36,7 +36,7 @@ class ColorLayer extends Renderable {
 
     }
 
-    onResetEvent(name, color, z) {
+    onResetEvent(name, color, z = 0) {
         // apply given parameters
         this.name = name;
         this.pos.z = z;
make the z argument optional

it's overwritten anyway when added to the game world, but still cleaner this way (instead of setting to "undefined")