diff --git a/src/Common.CoreLib/WebSocket/WebSocketServer.cs b/src/Common.CoreLib/WebSocket/WebSocketServer.cs
index 6e925b3b3..9864f21c6 100644
--- a/src/Common.CoreLib/WebSocket/WebSocketServer.cs
+++ b/src/Common.CoreLib/WebSocket/WebSocketServer.cs
@@ -41,7 +41,7 @@ namespace System.Net.WebSocket
                 throw new ArgumentException("Invalid IP address");
             var random = new Random();
             port = random.Next(10000, 25564);
-            while (!IsPortOccupedFun(port))
+            while (IsPortOccupedFun(port))
             {
                 port = random.Next(10000, 25564);
             }