diff --git a/MapControl/Shared/MapProjection.cs b/MapControl/Shared/MapProjection.cs
index aa0a59d6..125e85e4 100644
--- a/MapControl/Shared/MapProjection.cs
+++ b/MapControl/Shared/MapProjection.cs
@@ -187,7 +187,7 @@ namespace MapControl
         public void SetViewportTransform(Location projectionCenter, Location mapCenter, Point viewportCenter, double zoomLevel, double rotation)
         {
             ProjectionCenter = projectionCenter;
-            ViewportScale = Math.Pow(2d, zoomLevel) * 256d / (360d * TrueScale);
+            ViewportScale = 256d * Math.Pow(2d, zoomLevel) / (360d * TrueScale);
             ViewportRotation = rotation;
 
             var center = LocationToPoint(mapCenter);
diff --git a/MapControl/Shared/MapTileLayer.cs b/MapControl/Shared/MapTileLayer.cs
index 9c7383a7..8432c8c2 100644
--- a/MapControl/Shared/MapTileLayer.cs
+++ b/MapControl/Shared/MapTileLayer.cs
@@ -22,12 +22,13 @@ namespace MapControl
     public class MapTileLayer : MapTileLayerBase
     {
         public const int TileSize = 256;
-        public const double MapSize = 2 * Math.PI * MapProjection.Wgs84EquatorialRadius;
-        public static readonly Point TileGridTopLeft = new Point(-MapSize / 2, MapSize / 2);
+
+        public static readonly Point TileGridTopLeft = new Point(
+            -180d * MapProjection.Wgs84MetersPerDegree, 180d * MapProjection.Wgs84MetersPerDegree);
 
         public static double TileGridScale(int zoomLevel)
         {
-            return (TileSize << zoomLevel) / MapSize;
+            return (TileSize << zoomLevel) / (360d * MapProjection.Wgs84MetersPerDegree);
         }
 
         /// <summary>