diff --git a/lib/OpenLayers/Layer/Grid.js b/lib/OpenLayers/Layer/Grid.js
index 610ad5a200..6737fefab2 100644
--- a/lib/OpenLayers/Layer/Grid.js
+++ b/lib/OpenLayers/Layer/Grid.js
@@ -243,7 +243,7 @@ OpenLayers.Layer.Grid.prototype =
 
         var iRow = 0;
         var iCell = -1;
-        var direction = directions.indexOf("right");
+        var direction = OpenLayers.Util.indexOf(directions, "right");
         var directionsTried = 0;
         
         while( directionsTried < directions.length) {
diff --git a/lib/OpenLayers/Map.js b/lib/OpenLayers/Map.js
index d70041b47d..6712d8b86e 100644
--- a/lib/OpenLayers/Map.js
+++ b/lib/OpenLayers/Map.js
@@ -359,7 +359,7 @@ OpenLayers.Map.prototype = {
         if (newBaseLayer != oldBaseLayer) {
           
             // is newBaseLayer an already loaded layer?
-            if (this.layers.indexOf(newBaseLayer) != -1) {
+            if (OpenLayers.Util.indexOf(this.layers, newBaseLayer) != -1) {
 
                 // make the old base layer invisible 
                 if (oldBaseLayer != null) {
diff --git a/lib/OpenLayers/Util.js b/lib/OpenLayers/Util.js
index 45e84050a9..639b1a8abe 100644
--- a/lib/OpenLayers/Util.js
+++ b/lib/OpenLayers/Util.js
@@ -60,6 +60,21 @@ OpenLayers.Util.clearArray = function(array) {
     array.length = 0;
 };
 
+/** Seems to exist already in FF, but not in MOZ.
+ * 
+ * @param {Array} array
+ * @param {Object} obj
+ */
+OpenLayers.Util.indexOf = function(array, obj) {
+
+    for(var i=0; i < array.length; i++) {
+        if (array[i] == obj) return i;
+    }
+    return -1;   
+};
+
+
+
 /**
  * @param {String} id
  * @param {OpenLayers.Pixel} px
diff --git a/tests/test_Map.html b/tests/test_Map.html
index 29f0f69c3f..15d6554ee4 100644
--- a/tests/test_Map.html
+++ b/tests/test_Map.html
@@ -125,7 +125,8 @@
         map.setCenter(new OpenLayers.LonLat(0, 0), 0);
 
         map.addPopup(popup);
-        t.eq(map.popups.indexOf(popup), 0, "popup successfully added to Map's internal popups array");
+        var pIndex = OpenLayers.Util.indexOf(map.popups, popup);
+        t.eq(pIndex, 0, "popup successfully added to Map's internal popups array");
 
         var nodes = map.layerContainerDiv.childNodes;
         
@@ -140,7 +141,8 @@
 
         
         map.removePopup(popup);
-        t.eq(map.popups.indexOf(popup), -1, "popup successfully removed from Map's internal popups array");
+        var pIndex = OpenLayers.Util.indexOf(map.popups, popup);
+        t.eq(pIndex, -1, "popup successfully removed from Map's internal popups array");
 
         var found = false;
         for (var i=0; i < nodes.length; i++) {