diff --git a/td/telegram/net/ConnectionCreator.cpp b/td/telegram/net/ConnectionCreator.cpp
index 4ff55f9dd..a002623ba 100644
--- a/td/telegram/net/ConnectionCreator.cpp
+++ b/td/telegram/net/ConnectionCreator.cpp
@@ -651,7 +651,11 @@ void ConnectionCreator::client_loop(ClientInfo &client) {
     auto r_socket_fd = [&, dc_id = client.dc_id]() -> Result<SocketFd> {
       TRY_RESULT(info, dc_options_set_.find_connection(dc_id, allow_media_only, use_proxy));
       stat = info.stat;
-      int16 raw_dc_id = narrow_cast<int16>(info.option->is_media_only() ? -dc_id.get_raw_id() : dc_id.get_raw_id());
+      int32 int_dc_id = dc_id.get_raw_id();
+      if (G()->is_test_dc()) {
+        int_dc_id += 10000;
+      }
+      int16 raw_dc_id = narrow_cast<int16>(info.option->is_media_only() ? -int_dc_id : int_dc_id);
 
       if (use_mtproto_proxy) {
         TRY_RESULT(secret, hex_decode(proxy->secret()));