diff --git a/Password_manager/include/arg_func.h b/Password_manager/include/arg_func.h
index d671697..cd4d979 100644
--- a/Password_manager/include/arg_func.h
+++ b/Password_manager/include/arg_func.h
@@ -16,7 +16,8 @@ enum class Arg
 	Input, // input password for label
 	Change, // change main password
 	Show, // show password for label
-	Error // error
+	Error, // error
+	Username, // update username
 };
 
 Arg get_args(int argc, char** argv, char** label);
@@ -27,6 +28,8 @@ LoginInfoPointer arg_generate(Buffer& decrypted_buffer, Buffer& encrypted_buffer
 
 std::optional<LoginInfoPointer> arg_input(Buffer& decrypted_buffer, Buffer& encrypted_buffer, const char* label, Cryptography& crypto);
 
+void arg_username(Buffer& decrypted_buffer, Buffer& encrypted_buffer, const char* label, Cryptography& crypto);
+
 void arg_list(Buffer& decrypted_buffer);
 
 void arg_delete(Buffer& decrypted_buffer, Buffer& encrypted_buffer, const char* label, Cryptography& crypto);
diff --git a/Password_manager/source/arg_func.cpp b/Password_manager/source/arg_func.cpp
index fee11a6..aecdf14 100644
--- a/Password_manager/source/arg_func.cpp
+++ b/Password_manager/source/arg_func.cpp
@@ -20,6 +20,7 @@ void print_args()
 	printf_s(" -i <label> \t input password for this label (or update if exists)\n");
 	printf_s(" -d <label> \t delete password of this label\n");
 	printf_s(" -s <label> \t show password for this label\n");
+	printf_s(" -u <label> \t update username for this label\n");
 	printf_s(" -l         \t list all labels\n");
 	printf_s(" -p         \t print all passwords\n");
 	printf_s(" -c         \t change master password\n");
@@ -54,6 +55,7 @@ Arg get_args(int argc, char** argv, char** label) {
 	if (!strcmp("-d", argv[1])) return Arg::Delete;
 	if (!strcmp("-i", argv[1]))	return Arg::Input;
 	if (!strcmp("-s", argv[1])) return Arg::Show;
+	if (!strcmp("-u", argv[1])) return Arg::Username;
 
 	return Arg::Error;
 }
@@ -128,6 +130,29 @@ std::optional<LoginInfoPointer> arg_input(Buffer& decrypted_buffer, Buffer& encr
 	return save(decrypted_buffer, encrypted_buffer, label, crypto, username, password);
 }
 
+void arg_username(Buffer& decrypted_buffer, Buffer& encrypted_buffer, const char* label, Cryptography& crypto)
+{
+	int pass = find_logininfo_in_buffer(decrypted_buffer, label);
+	if (pass < 0)
+	{
+		printf_s("LoginInfo not found\n");
+		return;
+	}
+
+	LoginInfoPointer lip = get_logininfo_pointer_from_buffer(decrypted_buffer, pass);
+	std::string password = lip.password;
+	std::string name = lip.label;
+
+	printf_s("Input username for %s: ", name.c_str());
+	std::string username;
+	std::getline(std::cin, username);
+
+	delete_logininfo_from_buffer(decrypted_buffer, pass);
+	add_logininfo_to_buffer(decrypted_buffer, name.c_str(), username.c_str(), password.c_str());
+	crypto.encrypt(&decrypted_buffer, &encrypted_buffer);
+	encrypted_buffer.save_to_file();
+}
+
 void arg_list(Buffer& decrypted_buffer)
 {
 	Index* index = (Index*)decrypted_buffer.buffer;
diff --git a/Password_manager/source/main.cpp b/Password_manager/source/main.cpp
index ec6ba5d..cf11224 100644
--- a/Password_manager/source/main.cpp
+++ b/Password_manager/source/main.cpp
@@ -60,9 +60,13 @@ int main()
 		login_info = arg_input(decrypted_buffer, encrypted_buffer, label, crypto);
 		break;
 
+	case Arg::Username:
+		arg_username(decrypted_buffer, encrypted_buffer, label, crypto);
+		break;
+
 	case Arg::Change:
 		arg_change(decrypted_buffer, encrypted_buffer, user_pass, crypto);
-
+		break;
 
 	case Arg::Show:
 		arg_show(decrypted_buffer, label);
@@ -138,9 +142,13 @@ int main(int argc, char** argv)
 		login_info = arg_input(decrypted_buffer, encrypted_buffer, label, crypto);
 		break;
 
+	case Arg::Username:
+		arg_username(decrypted_buffer, encrypted_buffer, label, crypto);
+		break;
+
 	case Arg::Change:
 		arg_change(decrypted_buffer, encrypted_buffer, user_pass, crypto);
-
+		break;
 
 	case Arg::Show:
 		arg_show(decrypted_buffer, label);