diff --git a/src/ol/tilebounds.js b/src/ol/tilebounds.js
index efe576df84..fbf61b7de4 100644
--- a/src/ol/tilebounds.js
+++ b/src/ol/tilebounds.js
@@ -16,6 +16,9 @@ goog.require('ol.TileCoord');
  */
 ol.TileBounds = function(top, right, bottom, left) {
 
+  goog.asserts.assert(top <= bottom);
+  goog.asserts.assert(left <= right);
+
   goog.base(this, top, right, bottom, left);
 
 };
diff --git a/src/ol/tilegrid_test.js b/src/ol/tilegrid_test.js
index 9dbe312e5e..41ee4ca547 100644
--- a/src/ol/tilegrid_test.js
+++ b/src/ol/tilegrid_test.js
@@ -214,9 +214,9 @@ function testGetExtentTileBounds() {
 
   tileBounds = tileGrid.getExtentTileBounds(3, e);
   window.console.log(tileBounds);
-  assertEquals(9, tileBounds.top);
+  assertEquals(8, tileBounds.top);
   assertEquals(5, tileBounds.right);
-  assertEquals(8, tileBounds.bottom);
+  assertEquals(9, tileBounds.bottom);
   assertEquals(4, tileBounds.left);
 
 }