diff --git a/src/tilesource.js b/src/tilesource.js
index 32f10da8..aab7f134 100644
--- a/src/tilesource.js
+++ b/src/tilesource.js
@@ -284,14 +284,10 @@ $.TileSource.prototype = {
         // see https://github.com/openseadragon/openseadragon/issues/22
         // we use the tilesources implementation of getLevelScale to generate
         // a memoized re-implementation
-        var maxLevel = Math.ceil(
-                Math.log( Math.max( this.dimensions.x, this.dimensions.y ) ) /
-                Math.log( 2 )
-            ),
-            levelScaleCache = {},
+        var levelScaleCache = {},
             i;
-        for( i = 0; i <= maxLevel; i++ ){
-            levelScaleCache[ i ] = 1 / Math.pow(2, maxLevel - i);
+        for( i = 0; i <= this.maxLevel; i++ ){
+            levelScaleCache[ i ] = 1 / Math.pow(2, this.maxLevel - i);
         }
         this.getLevelScale = function( _level ){
             return levelScaleCache[ _level ];