diff --git a/src/Microsoft.DotNet.Wpf/src/Shared/MS/Win32/HwndWrapper.cs b/src/Microsoft.DotNet.Wpf/src/Shared/MS/Win32/HwndWrapper.cs
index c6672b0fede..d8f01a0d49c 100644
--- a/src/Microsoft.DotNet.Wpf/src/Shared/MS/Win32/HwndWrapper.cs
+++ b/src/Microsoft.DotNet.Wpf/src/Shared/MS/Win32/HwndWrapper.cs
@@ -95,10 +95,11 @@ public HwndWrapper(
             // Register will fail if the string gets over 255 in length.
             // So limit each part to a reasonable amount.
             string appName;
-            if(null != AppDomain.CurrentDomain.FriendlyName && 128 <= AppDomain.CurrentDomain.FriendlyName.Length)
-                appName = AppDomain.CurrentDomain.FriendlyName.Substring(0, 128);
+            string currentDomainFriendlyName = AppDomain.CurrentDomain.FriendlyName;
+            if (null != currentDomainFriendlyName && 128 <= currentDomainFriendlyName.Length)
+                appName = currentDomainFriendlyName[..128];
             else
-                appName = AppDomain.CurrentDomain.FriendlyName;
+                appName = currentDomainFriendlyName;
 
             string threadName;
             if(null != Thread.CurrentThread.Name && 64 <= Thread.CurrentThread.Name.Length)