diff --git a/lib/OpenLayers/Projection.js b/lib/OpenLayers/Projection.js
index 03d64e6935..8b45639696 100644
--- a/lib/OpenLayers/Projection.js
+++ b/lib/OpenLayers/Projection.js
@@ -62,7 +62,7 @@ OpenLayers.Projection = OpenLayers.Class({
     initialize: function(projCode, options) {
         OpenLayers.Util.extend(this, options);
         this.projCode = projCode;
-        if (window.Proj4js) {
+        if (typeof Proj4js == "object") {
             this.proj = new Proj4js.Proj(projCode);
         }
     },
@@ -115,7 +115,7 @@ OpenLayers.Projection = OpenLayers.Class({
             if (!(p instanceof OpenLayers.Projection)) {
                 p = new OpenLayers.Projection(p);
             }
-            if (window.Proj4js && this.proj.defData && p.proj.defData) {
+            if ((typeof Proj4js == "object") && this.proj.defData && p.proj.defData) {
                 equals = this.proj.defData.replace(this.titleRegEx, "") ==
                     p.proj.defData.replace(this.titleRegEx, "");
             } else if (p.getCode) {