diff --git a/lib/OpenLayers/Layer/WMS.js b/lib/OpenLayers/Layer/WMS.js
index 17e3d12cae..6c01f8cd51 100644
--- a/lib/OpenLayers/Layer/WMS.js
+++ b/lib/OpenLayers/Layer/WMS.js
@@ -38,6 +38,14 @@ OpenLayers.Layer.WMS.prototype =
                            );
         }
     },    
+
+    
+    /** WFS layer is never a base class. 
+     * @type Boolean
+     */
+    isBaseLayer: function() {
+        return (this.params.TRANSPARENT != true);
+    },
     
     /**
     * @param {String} name