diff --git a/src/libraries/System.Private.CoreLib/src/System/Threading/TimerQueue.Portable.cs b/src/libraries/System.Private.CoreLib/src/System/Threading/TimerQueue.Portable.cs
index 0e7892d36f3d9..40983768c823f 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Threading/TimerQueue.Portable.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Threading/TimerQueue.Portable.cs
@@ -73,7 +73,7 @@ private bool SetTimer(uint actualDuration)
         }
 
         /// <summary>
-        /// This method is executed on a dedicated a timer thread. Its purpose is
+        /// This method is executed on a dedicated timer thread. Its purpose is
         /// to handle timer requests and notify the TimerQueue when a timer expires.
         /// </summary>
         private static void TimerThread()