diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8c17b91c2..3ec8c4566 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -228,6 +228,11 @@ endif()
 if (GCC AND NOT (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.0))
   add_cxx_compiler_flag("-Wno-maybe-uninitialized")  # too much false positives
 endif()
+if (GCC AND NOT (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.0))
+  # warns about a lot of "return std::move", which are not redundant for compilers without fix for DR 1579, i.e. GCC 4.9 or clang 3.8
+  # see http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1579
+  add_cxx_compiler_flag("-Wno-redundant-move")
+endif()
 
 #set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -isystem /usr/include/c++/v1")
 #set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")
diff --git a/td/telegram/ContactsManager.cpp b/td/telegram/ContactsManager.cpp
index 022254dc5..5001693a2 100644
--- a/td/telegram/ContactsManager.cpp
+++ b/td/telegram/ContactsManager.cpp
@@ -7582,7 +7582,7 @@ void ContactsManager::on_get_channel_participants_success(
     total_count = static_cast<int32>(result.size());
   }
 
-  const auto max_participant_count = get_channel_type(channel_id) == ChannelType::Megagroup ? 9950 : 195;
+  const auto max_participant_count = get_channel_type(channel_id) == ChannelType::Megagroup ? 9750 : 195;
   auto participant_count =
       filter.is_recent() && total_count != 0 && total_count < max_participant_count ? total_count : -1;
   int32 administrator_count = filter.is_administrators() ? total_count : -1;
diff --git a/tdactor/td/actor/impl/Scheduler.h b/tdactor/td/actor/impl/Scheduler.h
index fcb613c39..7adf451eb 100644
--- a/tdactor/td/actor/impl/Scheduler.h
+++ b/tdactor/td/actor/impl/Scheduler.h
@@ -237,7 +237,7 @@ void Scheduler::send_lambda(ActorRef actor_ref, EventT &&lambda) {
                               [&]() {
                                 auto event = Event::lambda(std::forward<EventT>(lambda));
                                 event.set_link_token(actor_ref.token());
-                                return std::move(event);
+                                return event;
                               });
 }
 
@@ -251,7 +251,7 @@ void Scheduler::send_closure(ActorRef actor_ref, EventT &&closure) {
                               [&]() {
                                 auto event = Event::immediate_closure(std::forward<EventT>(closure));
                                 event.set_link_token(actor_ref.token());
-                                return std::move(event);
+                                return event;
                               });
 }