diff --git a/lib/OpenLayers/Map.js b/lib/OpenLayers/Map.js
index 708105fa69..920816d8bc 100644
--- a/lib/OpenLayers/Map.js
+++ b/lib/OpenLayers/Map.js
@@ -258,8 +258,10 @@ OpenLayers.Map.prototype = {
     */
     getZoomForExtent: function (bounds) {
         var size = this.getSize();
-        var deg_per_pixel = (bounds.getWidth() > bounds.getHeight() ? bounds.getWidth() / size.w : bounds.getHeight() / size.h);
-        var zoom = -( Math.log(deg_per_pixel / this.maxResolution) / Math.log(2) );
+        var width = bounds.getWidth();
+        var height = bounds.getHeight();
+        var deg_per_pixel = (width > height ? width / size.w : height / size.h);
+        var zoom = Math.log(this.maxResolution / deg_per_pixel) / Math.log(2);
         return Math.floor(Math.max(zoom, 0)); 
     },