diff --git a/code/map_data.js b/code/map_data.js
index 10372b77..1edd99bc 100644
--- a/code/map_data.js
+++ b/code/map_data.js
@@ -29,7 +29,7 @@ window.requestData = function() {
   for (var x = x1; x <= x2; x++) {
     for (var y = y1; y <= y2; y++) {
       var tile_id = pointToTileId(z, x, y);
-      var bucket = Math.floor(x / 2) + "" + Math.floor(y / 2);
+      var bucket = (x % 2) + ":" + (y % 2);
       if (!tiles[bucket])
         tiles[bucket] = [];
       tiles[bucket].push(generateBoundsParams(
@@ -44,6 +44,7 @@ window.requestData = function() {
 
   // Reset previous result of Portal Render Limit handler
   portalRenderLimit.init();
+
   // finally send ajax requests
   $.each(tiles, function(ind, tls) {
     data = { zoom: z };