diff --git a/src/markerclusterer.js b/src/markerclusterer.js
index 554fcec..d7b3ad2 100755
--- a/src/markerclusterer.js
+++ b/src/markerclusterer.js
@@ -695,7 +695,7 @@ MarkerClusterer.prototype.repaint = function() {
 
   // Remove the old clusters.
   // Do it in a timeout so the other clusters have been drawn first.
-  window.setTimeout(function() {
+  setTimeout(function() {
     for (var i = 0, cluster; cluster = oldClusters[i]; i++) {
       cluster.remove();
     }
@@ -1267,7 +1267,9 @@ ClusterIcon.prototype.createCss = function(pos) {
 // Export Symbols for Closure
 // If you are not going to compile with closure then you can remove the
 // code below.
-window['MarkerClusterer'] = MarkerClusterer;
+if (typeof window !== 'undefined') {
+  window['MarkerClusterer'] = MarkerClusterer; 
+}
 MarkerClusterer.prototype['addMarker'] = MarkerClusterer.prototype.addMarker;
 MarkerClusterer.prototype['addMarkers'] = MarkerClusterer.prototype.addMarkers;
 MarkerClusterer.prototype['clearMarkers'] =