diff --git a/lib/OpenLayers/Layer/MapServer.js b/lib/OpenLayers/Layer/MapServer.js
index 2cb9948469..e9d4c4ec02 100644
--- a/lib/OpenLayers/Layer/MapServer.js
+++ b/lib/OpenLayers/Layer/MapServer.js
@@ -144,19 +144,19 @@ OpenLayers.Layer.MapServer = OpenLayers.Class(OpenLayers.Layer.Grid, {
         // use layer's url unless altUrl passed in
         var url = (altUrl == null) ? this.url : altUrl;
         
-        // if url is not a string, it should be an array of strings, 
-        //  in which case we will randomly select one of them in order
-        //  to evenly distribute requests to different urls.
-        if (typeof url == "object") {
-            url = url[Math.floor(Math.random()*url.length)];
-        }   
-        // requestString always starts with url
-        var requestString = url;        
-
         // create a new params hashtable with all the layer params and the 
         // new params together. then convert to string
         var allParams = OpenLayers.Util.extend({}, this.params);
         allParams = OpenLayers.Util.extend(allParams, newParams);
+        var paramsString = OpenLayers.Util.getParameterString(allParams);
+        
+        // if url is not a string, it should be an array of strings, 
+        // in which case we will deterministically select one of them in 
+        // order to evenly distribute requests to different urls.
+        if (url instanceof Array) {
+            url = this.selectUrl(paramsString, url);
+        }   
+        
         // ignore parameters that are already in the url search string
         var urlParams = OpenLayers.Util.upperCaseObject(
                             OpenLayers.Util.getParameters(url));
@@ -165,8 +165,11 @@ OpenLayers.Layer.MapServer = OpenLayers.Class(OpenLayers.Layer.Grid, {
                 delete allParams[key];
             }
         }
-        var paramsString = OpenLayers.Util.getParameterString(allParams);
+        paramsString = OpenLayers.Util.getParameterString(allParams);
         
+        // requestString always starts with url
+        var requestString = url;        
+
         // MapServer needs '+' seperating things like bounds/height/width.
         //   Since typically this is URL encoded, we use a slight hack: we
         //  depend on the list-like functionality of getParameterString to
diff --git a/tests/Layer/test_MapServer.html b/tests/Layer/test_MapServer.html
index 0ba06d7820..3b3e6d270e 100644
--- a/tests/Layer/test_MapServer.html
+++ b/tests/Layer/test_MapServer.html
@@ -156,9 +156,7 @@
     }
 
     function test_07_Layer_MapServer_getFullRequestString (t) {
-
-        
-        t.plan( 1 );
+        t.plan( 3 );
         var map = new OpenLayers.Map('map');
         tUrl = "http://labs.metacarta.com/cgi-bin/mapserv";
         tParams = { layers: 'basic', 
@@ -178,6 +176,23 @@
         
         t.eq(str, sStr , "getFullRequestString() works");
         map.destroy();
+        
+        tUrl = ["http://octo.metacarta.com/cgi-bin/mapserv","http://labs.metacarta.com/cgi-bin/mapserv"];
+        layer = new OpenLayers.Layer.MapServer(name, tUrl, tParams, null);
+        str = layer.getFullRequestString({'c':'d'});
+        t.eq(str, tUrl[1] + '?' + OpenLayers.Util.getParameterString(OpenLayers.Util.extend(tParams,{'c':'d'})), "getFullRequestString() works for list of two urls and is deterministic");
+        layer.destroy();
+        var tParams = {
+                 layers: 'basic', 
+                 format: 'png',
+                 mode: 'map',
+                 map_imagetype: 'png'
+        };
+        tUrl = ["http://octo.metacarta.com/cgi-bin/mapserv","http://labs.metacarta.com/cgi-bin/mapserv"];
+        layer = new OpenLayers.Layer.MapServer(name, tUrl, tParams, null);
+        str = layer.getFullRequestString({'a':'b'});
+        t.eq(str, tUrl[0] + '?' + OpenLayers.Util.getParameterString(OpenLayers.Util.extend(tParams,{'a':'b'})), "getFullRequestString() works for list of two urls and is deterministic");
+        layer.destroy();
 
     }