diff --git a/td/telegram/ConfigManager.cpp b/td/telegram/ConfigManager.cpp
index 57c8faf16..63eba3e1b 100644
--- a/td/telegram/ConfigManager.cpp
+++ b/td/telegram/ConfigManager.cpp
@@ -1387,8 +1387,8 @@ void ConfigManager::process_config(tl_object_ptr<telegram_api::config> config) {
   shared_config.set_option_integer("call_packet_timeout_ms", config->call_packet_timeout_ms_);
   shared_config.set_option_integer("call_receive_timeout_ms", config->call_receive_timeout_ms_);
 
-  shared_config.set_option_integer("message_text_length_max", config->message_length_max_);
-  shared_config.set_option_integer("message_caption_length_max", config->caption_length_max_);
+  shared_config.set_option_integer("message_text_length_max", clamp(config->message_length_max_, 4096, 1000000));
+  shared_config.set_option_integer("message_caption_length_max", clamp(config->caption_length_max_, 1024, 1000000));
 
   if (config->gif_search_username_.empty()) {
     shared_config.set_option_empty("animation_search_bot_username");
diff --git a/td/telegram/MessageEntity.cpp b/td/telegram/MessageEntity.cpp
index 4342e17b0..37a9f5f3c 100644
--- a/td/telegram/MessageEntity.cpp
+++ b/td/telegram/MessageEntity.cpp
@@ -3657,6 +3657,11 @@ vector<MessageEntity> get_message_entities(vector<tl_object_ptr<secret_api::Mess
         UNREACHABLE();
     }
   }
+
+  constexpr size_t MAX_SECRET_CHAT_ENTITIES = 1000;
+  if (entities.size() >= MAX_SECRET_CHAT_ENTITIES) {
+    entities.resize(MAX_SECRET_CHAT_ENTITIES);
+  }
   return entities;
 }