diff --git a/td/telegram/MessagesManager.cpp b/td/telegram/MessagesManager.cpp
index 1d412c704..9a7bf71a0 100644
--- a/td/telegram/MessagesManager.cpp
+++ b/td/telegram/MessagesManager.cpp
@@ -17767,6 +17767,8 @@ void MessagesManager::send_update_chat_read_inbox(const Dialog *d, bool force, c
                                          << source;
     on_dialog_updated(d->dialog_id, source);
     if (!force && (running_get_difference_ || running_get_channel_difference(d->dialog_id))) {
+      LOG(INFO) << "Postpone updateChatReadInbox in " << d->dialog_id << "(" << get_dialog_title(d->dialog_id) << ") to "
+                << d->server_unread_count << " + " << d->local_unread_count << " from " << source;
       postponed_chat_read_inbox_updates_.insert(d->dialog_id);
     } else {
       postponed_chat_read_inbox_updates_.erase(d->dialog_id);
diff --git a/td/telegram/td_json_client.h b/td/telegram/td_json_client.h
index b036e9525..a5db0dfb3 100644
--- a/td/telegram/td_json_client.h
+++ b/td/telegram/td_json_client.h
@@ -68,6 +68,8 @@ TDJSON_EXPORT void td_json_client_send(void *client, const char *request);
 /**
  * Receives incoming updates and request responses from the TDLib client. May be called from any thread, but
  * shouldn't be called simultaneously from two different threads.
+ * Returned pointer will be deallocated by TDLib during next call to td_json_client_receive or td_json_client_execute
+ * in the same thread, so it can't be used after that.
  * \param[in] client The client.
  * \param[in] timeout Maximum number of seconds allowed for this function to wait for new data.
  * \return JSON-serialized null-terminated incoming update or request response. May be NULL if the timeout expires.
@@ -77,6 +79,8 @@ TDJSON_EXPORT const char *td_json_client_receive(void *client, double timeout);
 /**
  * Synchronously executes TDLib request. May be called from any thread.
  * Only a few requests can be executed synchronously.
+ * Returned pointer will be deallocated by TDLib during next call to td_json_client_receive or td_json_client_execute
+ * in the same thread, so it can't be used after that.
  * \param[in] client The client.
  * \param[in] request JSON-serialized null-terminated request to TDLib.
  * \return JSON-serialized null-terminated request response. May be NULL if the request can't be parsed.