diff --git a/MapControl/Shared/TileSource.cs b/MapControl/Shared/TileSource.cs
index c1976025..e77fc241 100644
--- a/MapControl/Shared/TileSource.cs
+++ b/MapControl/Shared/TileSource.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Security.Policy;
 using System.Text;
 using System.Threading.Tasks;
 #if WPF
diff --git a/MapControl/Shared/WmtsTileLayer.cs b/MapControl/Shared/WmtsTileLayer.cs
index ba9ca8ba..5bbb78de 100644
--- a/MapControl/Shared/WmtsTileLayer.cs
+++ b/MapControl/Shared/WmtsTileLayer.cs
@@ -131,12 +131,7 @@ namespace MapControl
             }
             else if (UpdateChildLayers(tileMatrixSet))
             {
-                var tileSource = new WmtsTileSource
-                {
-                    UriTemplate = TileUriTemplate,
-                    TileMatrixSet = tileMatrixSet
-                };
-
+                var tileSource = new WmtsTileSource(tileMatrixSet, TileUriTemplate);
                 var cacheName = SourceName;
 
                 if (!string.IsNullOrEmpty(cacheName))
diff --git a/MapControl/Shared/WmtsTileSource.cs b/MapControl/Shared/WmtsTileSource.cs
index 7810e507..dec386cc 100644
--- a/MapControl/Shared/WmtsTileSource.cs
+++ b/MapControl/Shared/WmtsTileSource.cs
@@ -1,24 +1,30 @@
 using System;
+using System.Collections.Generic;
 using System.Text;
 
 namespace MapControl
 {
     public class WmtsTileSource : UriTileSource
     {
-        public WmtsTileMatrixSet TileMatrixSet { get; set; }
+        private readonly IList<WmtsTileMatrix> tileMatrixes;
+
+        public WmtsTileSource(WmtsTileMatrixSet tileMatrixSet, string uriTemplate)
+        {
+            tileMatrixes = tileMatrixSet.TileMatrixes;
+            UriTemplate = uriTemplate.Replace("{TileMatrixSet}", tileMatrixSet.Identifier);
+        }
 
         public override Uri GetUri(int zoomLevel, int column, int row)
         {
             Uri uri = null;
 
             if (UriTemplate != null &&
-                TileMatrixSet != null &&
-                TileMatrixSet.TileMatrixes.Count > zoomLevel)
+                tileMatrixes != null &&
+                tileMatrixes.Count > zoomLevel)
             {
                 var uriBuilder = new StringBuilder(UriTemplate);
 
-                uriBuilder.Replace("{TileMatrixSet}", TileMatrixSet.Identifier);
-                uriBuilder.Replace("{TileMatrix}", TileMatrixSet.TileMatrixes[zoomLevel].Identifier);
+                uriBuilder.Replace("{TileMatrix}", tileMatrixes[zoomLevel].Identifier);
                 uriBuilder.Replace("{TileCol}", column.ToString());
                 uriBuilder.Replace("{TileRow}", row.ToString());