diff --git a/lib/OpenLayers/Map.js b/lib/OpenLayers/Map.js
index 51acbecb00..a06b4a9b57 100644
--- a/lib/OpenLayers/Map.js
+++ b/lib/OpenLayers/Map.js
@@ -138,14 +138,10 @@ OpenLayers.Map.prototype = {
     /**
     * @param {OpenLayers.Layer} layer
     */    
-    addLayer: function (layer, zIndex) {
+    addLayer: function (layer) {
         layer.setMap(this);
         layer.div.style.overflow = "";
-        if (zIndex) {
-            layer.div.style.zIndex = zIndex;
-        } else {
-            layer.div.style.zIndex = this.Z_INDEX_BASE['Layer'] + this.layers.length;
-        }
+        layer.div.style.zIndex = this.Z_INDEX_BASE['Layer'] + this.layers.length;
 
         if (layer.viewPortLayer) {
             this.viewPortDiv.appendChild(layer.div);