diff --git a/lib/OpenLayers/Control/OverviewMap.js b/lib/OpenLayers/Control/OverviewMap.js
index c075a45577..245113893f 100644
--- a/lib/OpenLayers/Control/OverviewMap.js
+++ b/lib/OpenLayers/Control/OverviewMap.js
@@ -453,7 +453,7 @@ OpenLayers.Control.OverviewMap = OpenLayers.Class(OpenLayers.Control, {
      */
     isSuitableOverview: function() {
         var mapExtent = this.map.getExtent();
-        var maxExtent = this.map.maxExtent;
+        var maxExtent = this.map.getMaxExtent();
         var testExtent = new OpenLayers.Bounds(
                                 Math.max(mapExtent.left, maxExtent.left),
                                 Math.max(mapExtent.bottom, maxExtent.bottom),