diff --git a/td/telegram/Log.cpp b/td/telegram/Log.cpp
index 230aab13..b712b821 100644
--- a/td/telegram/Log.cpp
+++ b/td/telegram/Log.cpp
@@ -11,8 +11,11 @@
 #include "td/utils/logging.h"
 #include "td/utils/Slice.h"
 
+#include <mutex>
+
 namespace td {
 
+static std::mutex log_mutex;
 static FileLog file_log;
 static TsLog ts_log(&file_log);
 static int64 max_log_file_size = 10 << 20;
@@ -24,6 +27,7 @@ static void fatal_error_callback_wrapper(CSlice message) {
 }
 
 bool Log::set_file_path(string file_path) {
+  std::lock_guard<std::mutex> lock(log_mutex);
   if (file_path.empty()) {
     log_interface = default_log_interface;
     return true;
@@ -38,17 +42,20 @@ bool Log::set_file_path(string file_path) {
 }
 
 void Log::set_max_file_size(int64 max_file_size) {
+  std::lock_guard<std::mutex> lock(log_mutex);
   max_log_file_size = max(max_file_size, static_cast<int64>(0));
   file_log.set_rotate_threshold(max_log_file_size);
 }
 
 void Log::set_verbosity_level(int new_verbosity_level) {
+  std::lock_guard<std::mutex> lock(log_mutex);
   if (0 <= new_verbosity_level && new_verbosity_level <= 1024) {
     SET_VERBOSITY_LEVEL(VERBOSITY_NAME(FATAL) + new_verbosity_level);
   }
 }
 
 void Log::set_fatal_error_callback(FatalErrorCallbackPtr callback) {
+  std::lock_guard<std::mutex> lock(log_mutex);
   if (callback == nullptr) {
     fatal_error_callback = nullptr;
     set_log_fatal_error_callback(nullptr);