diff --git a/lib/OpenLayers/Layer/WMS.js b/lib/OpenLayers/Layer/WMS.js
index 325e6c2404..dda8beadc0 100644
--- a/lib/OpenLayers/Layer/WMS.js
+++ b/lib/OpenLayers/Layer/WMS.js
@@ -155,9 +155,9 @@ OpenLayers.Layer.WMS = OpenLayers.Class(OpenLayers.Layer.Grid, {
         
         var imageSize = this.getImageSize(); 
         var newParams = {
-            BBOX: this.encodeBBOX ?  bounds.toBBOX() : bounds.toArray(),
-            WIDTH:imageSize.w,
-            HEIGHT:imageSize.h
+            'BBOX': this.encodeBBOX ?  bounds.toBBOX() : bounds.toArray(),
+            'WIDTH': imageSize.w,
+            'HEIGHT': imageSize.h
         };
         var requestString = this.getFullRequestString(newParams);
         return requestString;