diff --git a/td/mtproto/TlsInit.cpp b/td/mtproto/TlsInit.cpp
index 115512eb4..d36b94f39 100644
--- a/td/mtproto/TlsInit.cpp
+++ b/td/mtproto/TlsInit.cpp
@@ -157,7 +157,7 @@ class TlsHelloContext {
     return grease_.size();
   }
   Slice get_domain() const {
-    return domain_;
+    return Slice(domain_).substr(0, 255);
   }
 
  private:
diff --git a/td/telegram/net/Proxy.cpp b/td/telegram/net/Proxy.cpp
index db68882f3..b20c9478b 100644
--- a/td/telegram/net/Proxy.cpp
+++ b/td/telegram/net/Proxy.cpp
@@ -17,6 +17,9 @@ Result<Proxy> Proxy::from_td_api(string server, int port, td_api::ProxyType *pro
   if (server.empty()) {
     return Status::Error(400, "Server name can't be empty");
   }
+  if (server.size() > 255) {
+    return Status::Error(400, "Server name is too long");
+  }
   if (port <= 0 || port > 65535) {
     return Status::Error(400, "Wrong port number");
   }