diff --git a/src/Custom/RealtimeConversation/RealtimeConversationClient.cs b/src/Custom/RealtimeConversation/RealtimeConversationClient.cs
index 09a97f55..a7c63c35 100644
--- a/src/Custom/RealtimeConversation/RealtimeConversationClient.cs
+++ b/src/Custom/RealtimeConversation/RealtimeConversationClient.cs
@@ -87,7 +87,7 @@ private static Uri GetEndpoint(string model, OpenAIClientOptions options)
             uriBuilder.Path += uriBuilder.Path[uriBuilder.Path.Length - 1] == '/' ? "realtime" : "/realtime";
         }
 
-        uriBuilder.Query = $"?model={model}";
+        uriBuilder.Query = $"model={model}";
 
         return uriBuilder.Uri;
     }
@@ -101,4 +101,4 @@ internal void RaiseOnReceivingCommand(RealtimeConversationSession session, Binar
     {
         OnReceivingCommand?.Invoke(session, data);
     }
-}
\ No newline at end of file
+}