diff --git a/src/auth/auth.cpp b/src/auth/auth.cpp
index 46911b7..1185f33 100644
--- a/src/auth/auth.cpp
+++ b/src/auth/auth.cpp
@@ -31,6 +31,7 @@ void auth(const httplib::Request& request, httplib::Response& response)
     const std::string request_username = json_body["username"];
     const std::string request_password = json_body["password"];
 
+    std::lock_guard<std::mutex> lock(usersfilemutex);
     std::ifstream usersfile(USERS_FILE);
     nlohmann::json all_users = nlohmann::json::parse(usersfile);
     usersfile.close();
diff --git a/src/includes.hpp b/src/includes.hpp
index 440222d..dd5dfe8 100644
--- a/src/includes.hpp
+++ b/src/includes.hpp
@@ -11,5 +11,6 @@
 #define CHANGE_USER_REQUIRED_STRING R"({"required":"[token] or if you superuser [token,userid]","optional":"[username,password,is_superuser,group]"})"
 #define DELETE_USER_REQUIRED_STRING R"({"required":"[token] or if you superuser [token,userid]"})"
 #define USERS_FILE "users.json"
+static std::mutex usersfilemutex;
 
 #endif // INCLUDES_HPP
diff --git a/src/users/add_user.cpp b/src/users/add_user.cpp
index aef5cc9..004a36e 100644
--- a/src/users/add_user.cpp
+++ b/src/users/add_user.cpp
@@ -61,10 +61,13 @@ void add_user(const httplib::Request& request, httplib::Response& response)
         syslog(LOG_ERR, "access reject in add user request");
         return;
     }
-
-    std::ifstream usersfile(USERS_FILE);
-    nlohmann::json all_users = nlohmann::json::parse(usersfile);
-    usersfile.close();
+    nlohmann::json all_users;
+    {
+        std::lock_guard<std::mutex> lock(usersfilemutex);
+        std::ifstream usersfile(USERS_FILE);
+        all_users = nlohmann::json::parse(usersfile);
+        usersfile.close();
+    }
 
     nlohmann::json response_user_data = nullptr;
     for (nlohmann::json& user : all_users) {
@@ -102,6 +105,7 @@ void add_user(const httplib::Request& request, httplib::Response& response)
     new_user_data += "}";
     all_users.push_back(nlohmann::json::parse(new_user_data));
 
+    std::lock_guard<std::mutex> lock(usersfilemutex);
     std::ofstream usersfilew(USERS_FILE);
     usersfilew << all_users.dump(4);
     usersfilew.close();
diff --git a/src/users/change_password.cpp b/src/users/change_password.cpp
index 7670fad..9924f72 100644
--- a/src/users/change_password.cpp
+++ b/src/users/change_password.cpp
@@ -58,10 +58,13 @@ void change_password(const httplib::Request& request, httplib::Response& respons
         syslog(LOG_ERR, "access reject in change password request");
         return;
     }
-
-    std::ifstream usersfile(USERS_FILE);
-    nlohmann::json all_users = nlohmann::json::parse(usersfile);
-    usersfile.close();
+    nlohmann::json all_users;
+    {
+        std::lock_guard<std::mutex> lock(usersfilemutex);
+        std::ifstream usersfile(USERS_FILE);
+        all_users = nlohmann::json::parse(usersfile);
+        usersfile.close();
+    }
 
     std::string changepassuserid = userid;
     if (json_body["userid"] != nullptr) {
@@ -112,6 +115,7 @@ void change_password(const httplib::Request& request, httplib::Response& respons
         syslog(LOG_ERR, "can't find this user in change password request");
         return;
     }
+    std::lock_guard<std::mutex> lock(usersfilemutex);
     std::ofstream usersfilew(USERS_FILE);
     usersfilew << all_users.dump(4);
     usersfilew.close();
diff --git a/src/users/change_user.cpp b/src/users/change_user.cpp
index 386104f..9fb75d2 100644
--- a/src/users/change_user.cpp
+++ b/src/users/change_user.cpp
@@ -46,11 +46,13 @@ void change_user(const httplib::Request& request, httplib::Response& response)
         syslog(LOG_ERR, "access reject in change user request");
         return;
     }
-
-    std::ifstream usersfile(USERS_FILE);
-    nlohmann::json all_users = nlohmann::json::parse(usersfile);
-    usersfile.close();
-
+    nlohmann::json all_users;
+    {
+        std::lock_guard<std::mutex> lock(usersfilemutex);
+        std::ifstream usersfile(USERS_FILE);
+        all_users = nlohmann::json::parse(usersfile);
+        usersfile.close();
+    }
     std::string changeusruserid = userid;
     if (json_body["userid"] != nullptr) {
         changeusruserid = json_body["userid"];
@@ -103,6 +105,7 @@ void change_user(const httplib::Request& request, httplib::Response& response)
         syslog(LOG_ERR, "can't find this user in change user request");
         return;
     }
+    std::lock_guard<std::mutex> lock(usersfilemutex);
     std::ofstream usersfilew(USERS_FILE);
     usersfilew << all_users.dump(4);
     usersfilew.close();
diff --git a/src/users/delete_user.cpp b/src/users/delete_user.cpp
index 720169b..e1449ca 100644
--- a/src/users/delete_user.cpp
+++ b/src/users/delete_user.cpp
@@ -38,11 +38,13 @@ void delete_user(const httplib::Request& request, httplib::Response& response)
         syslog(LOG_ERR, "access reject in delete user request");
         return;
     }
-
-    std::ifstream usersfile(USERS_FILE);
-    nlohmann::json all_users = nlohmann::json::parse(usersfile);
-    usersfile.close();
-
+    nlohmann::json all_users;
+    {
+        std::lock_guard<std::mutex> lock(usersfilemutex);
+        std::ifstream usersfile(USERS_FILE);
+        all_users = nlohmann::json::parse(usersfile);
+        usersfile.close();
+    }
     std::string deluserid = userid;
     if (json_body["userid"] != nullptr) {
         deluserid = json_body["userid"];
@@ -79,6 +81,7 @@ void delete_user(const httplib::Request& request, httplib::Response& response)
         syslog(LOG_ERR, "can't find this user in delete user request");
         return;
     }
+    std::lock_guard<std::mutex> lock(usersfilemutex);
     std::ofstream usersfilew(USERS_FILE);
     usersfilew << all_users.dump(4);
     usersfilew.close();
diff --git a/src/users/get_all_users.cpp b/src/users/get_all_users.cpp
index 30fcc1a..63805cb 100644
--- a/src/users/get_all_users.cpp
+++ b/src/users/get_all_users.cpp
@@ -33,6 +33,7 @@ void get_all_users(const httplib::Request& request, httplib::Response& response)
         syslog(LOG_ERR, "access reject in get all user request");
         return;
     }
+    std::lock_guard<std::mutex> lock(usersfilemutex);
     std::ifstream usersfile(USERS_FILE);
     nlohmann::json all_users = nlohmann::json::parse(usersfile);
     usersfile.close();
diff --git a/src/users/get_user.cpp b/src/users/get_user.cpp
index 3106887..5ac932a 100644
--- a/src/users/get_user.cpp
+++ b/src/users/get_user.cpp
@@ -33,6 +33,7 @@ void get_user(const httplib::Request& request, httplib::Response& response)
         syslog(LOG_ERR, "access reject in get user request");
         return;
     }
+    std::lock_guard<std::mutex> lock(usersfilemutex);
     std::ifstream usersfile(USERS_FILE);
     nlohmann::json all_users = nlohmann::json::parse(usersfile);
     usersfile.close();