diff --git a/CryptoExchange.Net/Interfaces/IWebsocket.cs b/CryptoExchange.Net/Interfaces/IWebsocket.cs
index 374a8d1..7ef74e6 100644
--- a/CryptoExchange.Net/Interfaces/IWebsocket.cs
+++ b/CryptoExchange.Net/Interfaces/IWebsocket.cs
@@ -39,7 +39,7 @@ namespace CryptoExchange.Net.Interfaces
         /// <summary>
         /// Get reconntion url
         /// </summary>
-        Func<Task<Uri?>> GetReconnectionUrl { get; set; }
+        Func<Task<Uri?>>? GetReconnectionUrl { get; set; }
 
         /// <summary>
         /// Unique id for this socket