diff --git a/td/telegram/ConfigManager.cpp b/td/telegram/ConfigManager.cpp
index ffeadb10a..40442875a 100644
--- a/td/telegram/ConfigManager.cpp
+++ b/td/telegram/ConfigManager.cpp
@@ -406,6 +406,9 @@ ActorOwn<> get_full_config(DcOption option, Promise<FullConfig> promise, ActorSh
     void on_tmp_auth_key_updated(mtproto::AuthKey auth_key) final {
       // nop
     }
+    void on_server_salt_updated(std::vector<mtproto::ServerSalt> server_salts) final {
+      // nop
+    }
     void on_result(NetQueryPtr net_query) final {
       G()->net_query_dispatcher().dispatch(std::move(net_query));
     }
diff --git a/td/telegram/net/Session.h b/td/telegram/net/Session.h
index 2a8ebfb03..7ce60984e 100644
--- a/td/telegram/net/Session.h
+++ b/td/telegram/net/Session.h
@@ -61,9 +61,7 @@ class Session final
     virtual void request_raw_connection(unique_ptr<mtproto::AuthData> auth_data,
                                         Promise<unique_ptr<mtproto::RawConnection>>) = 0;
     virtual void on_tmp_auth_key_updated(mtproto::AuthKey auth_key) = 0;
-    virtual void on_server_salt_updated(std::vector<mtproto::ServerSalt> server_salts) {
-    }
-    // one still have to call close after on_closed
+    virtual void on_server_salt_updated(std::vector<mtproto::ServerSalt> server_salts) = 0;
     virtual void on_result(NetQueryPtr net_query) = 0;
   };
 
diff --git a/td/telegram/net/SessionProxy.cpp b/td/telegram/net/SessionProxy.cpp
index b8c04f50f..f9f31dd59 100644
--- a/td/telegram/net/SessionProxy.cpp
+++ b/td/telegram/net/SessionProxy.cpp
@@ -240,6 +240,7 @@ void SessionProxy::on_tmp_auth_key_updated(mtproto::AuthKey auth_key) {
   LOG(WARNING) << "Have tmp_auth_key " << auth_key.id() << ": " << state;
   tmp_auth_key_ = std::move(auth_key);
 }
+
 void SessionProxy::on_server_salt_updated(std::vector<mtproto::ServerSalt> server_salts) {
   server_salts_ = std::move(server_salts);
 }