diff --git a/td/telegram/DialogFilter.cpp b/td/telegram/DialogFilter.cpp
index b82a71118..2bedf7ebd 100644
--- a/td/telegram/DialogFilter.cpp
+++ b/td/telegram/DialogFilter.cpp
@@ -93,7 +93,12 @@ unique_ptr<DialogFilter> DialogFilter::get_dialog_filter(
 
 Result<unique_ptr<DialogFilter>> DialogFilter::create_dialog_filter(Td *td, DialogFilterId dialog_filter_id,
                                                                     td_api::object_ptr<td_api::chatFilter> filter) {
-  CHECK(filter != nullptr);
+  if (filter == nullptr) {
+    return Status::Error(400, "Chat filter must be non-empty");
+  }
+  if (!clean_input_string(filter->title_) || !clean_input_string(filter->icon_name_)) {
+    return Status::Error(400, "Strings must be encoded in UTF-8");
+  }
 
   auto dialog_filter = make_unique<DialogFilter>();
   dialog_filter->dialog_filter_id_ = dialog_filter_id;
diff --git a/td/telegram/Td.cpp b/td/telegram/Td.cpp
index bd7b355e9..c171bd477 100644
--- a/td/telegram/Td.cpp
+++ b/td/telegram/Td.cpp
@@ -6127,22 +6127,12 @@ void Td::on_request(uint64 id, const td_api::getRecommendedChatFilters &request)
 
 void Td::on_request(uint64 id, td_api::createChatFilter &request) {
   CHECK_IS_USER();
-  if (request.filter_ == nullptr) {
-    return send_error_raw(id, 400, "Chat filter must be non-empty");
-  }
-  CLEAN_INPUT_STRING(request.filter_->title_);
-  CLEAN_INPUT_STRING(request.filter_->icon_name_);
   CREATE_REQUEST_PROMISE();
   dialog_filter_manager_->create_dialog_filter(std::move(request.filter_), std::move(promise));
 }
 
 void Td::on_request(uint64 id, td_api::editChatFilter &request) {
   CHECK_IS_USER();
-  if (request.filter_ == nullptr) {
-    return send_error_raw(id, 400, "Chat filter must be non-empty");
-  }
-  CLEAN_INPUT_STRING(request.filter_->title_);
-  CLEAN_INPUT_STRING(request.filter_->icon_name_);
   CREATE_REQUEST_PROMISE();
   dialog_filter_manager_->edit_dialog_filter(DialogFilterId(request.chat_filter_id_), std::move(request.filter_),
                                              std::move(promise));