diff --git a/td/telegram/Client.cpp b/td/telegram/Client.cpp
index 8a171522..d6469328 100644
--- a/td/telegram/Client.cpp
+++ b/td/telegram/Client.cpp
@@ -269,7 +269,7 @@ Client::Client() : impl_(make_unique<Impl>()) {
   init_openssl_threads();
 }
 
-void Client::send(Request request) {
+void Client::send(Request &&request) {
   impl_->send(std::move(request));
 }
 
@@ -277,7 +277,7 @@ Client::Response Client::receive(double timeout) {
   return impl_->receive(timeout);
 }
 
-Client::Response Client::execute(Request request) {
+Client::Response Client::execute(Request &&request) {
   Response response;
   response.id = request.id;
   response.object = Td::static_request(std::move(request.function));
diff --git a/td/telegram/Client.h b/td/telegram/Client.h
index 11e49371..ccd891b0 100644
--- a/td/telegram/Client.h
+++ b/td/telegram/Client.h
@@ -77,7 +77,7 @@ class Client final {
    * Sends request to TDLib. May be called from any thread.
    * \param[in] request Request to TDLib.
    */
-  void send(Request request);
+  void send(Request &&request);
 
   /**
    * A response to a request, or an incoming update from TDLib.
@@ -109,7 +109,7 @@ class Client final {
    * \param[in] request Request to the TDLib.
    * \return The request response.
    */
-  static Response execute(Request request);
+  static Response execute(Request &&request);
 
   /**
    * Destroys the client and TDLib instance.
diff --git a/td/telegram/LogDotNet.cpp b/td/telegram/LogDotNet.cpp
index efe0ee81..26ec600b 100644
--- a/td/telegram/LogDotNet.cpp
+++ b/td/telegram/LogDotNet.cpp
@@ -17,8 +17,8 @@ using namespace CxCli;
 
 public ref class Log sealed {
 public:
-  static void SetFilePath(String^ filePath) {
-    ::td::Log::set_file_path(string_to_unmanaged(filePath));
+  static bool SetFilePath(String^ filePath) {
+    return ::td::Log::set_file_path(string_to_unmanaged(filePath));
   }
 
   static void SetMaxFileSize(std::int64_t maxFileSize) {
diff --git a/tdutils/td/utils/port/CxCli.h b/tdutils/td/utils/port/CxCli.h
index 3619387f..db9230ed 100644
--- a/tdutils/td/utils/port/CxCli.h
+++ b/tdutils/td/utils/port/CxCli.h
@@ -74,8 +74,11 @@ inline std::int64_t Increment(volatile std::int64_t &value) {
   return InterlockedIncrement64(&value);
 }
 
-inline std::string string_to_unmanaged(String^ string) {
-  return td::from_wstring(string->Data(), string->Length()).ok();
+inline std::string string_to_unmanaged(String^ str) {
+  if (!str) {
+    return std::string();
+  }
+  return td::from_wstring(str->Data(), str->Length()).ok();
 }
 
 inline String^ string_from_unmanaged(const std::string &from) {
@@ -117,8 +120,11 @@ inline std::int64_t Increment(std::int64_t %value) {
   return System::Threading::Interlocked::Increment(value);
 }
 
-inline std::string string_to_unmanaged(String^ string) {
-  return msclr::interop::marshal_as<std::string>(string);
+inline std::string string_to_unmanaged(String^ str) {
+  if (!str) {
+    return std::string();
+  }
+  return msclr::interop::marshal_as<std::string>(str);
 }
 
 inline String^ string_from_unmanaged(const std::string &from) {