diff --git a/MapControl/Shared/TileSource.cs b/MapControl/Shared/TileSource.cs
index 074f4f8d..eb444404 100644
--- a/MapControl/Shared/TileSource.cs
+++ b/MapControl/Shared/TileSource.cs
@@ -36,7 +36,7 @@ namespace MapControl
             {
                 uriTemplate = value;
 
-                if (Subdomains == null && uriTemplate != null && uriTemplate.Contains("{s}"))
+                if (uriTemplate != null && uriTemplate.Contains("{s}") && Subdomains == null)
                 {
                     Subdomains = new string[] { "a", "b", "c" }; // default OpenStreetMap subdomains
                 }