diff --git a/MapControl/Shared/WmsImageLayer.cs b/MapControl/Shared/WmsImageLayer.cs
index 9011ba36..1d4e1434 100644
--- a/MapControl/Shared/WmsImageLayer.cs
+++ b/MapControl/Shared/WmsImageLayer.cs
@@ -342,7 +342,7 @@ namespace MapControl
             return uri.Replace(" ", "%20");
         }
 
-        private List<string> supportedCrsIds;
+        private List<string> supportedCrsIds = [];
 
         private async void OnLoaded(object sender, RoutedEventArgs e)
         {