diff --git a/lib/OpenLayers/Layer.js b/lib/OpenLayers/Layer.js
index cb9b780d70..b929a58e27 100644
--- a/lib/OpenLayers/Layer.js
+++ b/lib/OpenLayers/Layer.js
@@ -508,8 +508,8 @@ OpenLayers.Layer.prototype = {
             var center = this.map.getCenter();
             var res  = this.map.getResolution();
         
-            var delta_x = viewPortPx.x - (size.w / 2);
-            var delta_y = viewPortPx.y - (size.h / 2);
+            var delta_x = viewPortPx.x - Math.ceil(size.w / 2);
+            var delta_y = viewPortPx.y - Math.ceil(size.h / 2);
             
             lonlat = new OpenLayers.LonLat(center.lon + delta_x * res ,
                                          center.lat - delta_y * res);