diff --git a/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/Stylus/Wisp/WispLogic.cs b/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/Stylus/Wisp/WispLogic.cs
index c6ebbbe6808..a5e0fc72a98 100644
--- a/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/Stylus/Wisp/WispLogic.cs
+++ b/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/Stylus/Wisp/WispLogic.cs
@@ -3726,7 +3726,7 @@ internal long IncrementVersion()
         /// Lock the access to coalesced moves as it's possible it can be accessed simultaneously from two
         /// PenThreads if the initial PenThread fills up with PenContexts.
         /// </summary>
-        object _coalesceLock = new object();
+        private readonly object _coalesceLock = new object();
 
 #if !MULTICAPTURE
         IInputElement _stylusCapture;