diff --git a/src/core/libraries/libsceuserservice.cpp b/src/core/libraries/libsceuserservice.cpp
index 1d80fff0..30a0344f 100644
--- a/src/core/libraries/libsceuserservice.cpp
+++ b/src/core/libraries/libsceuserservice.cpp
@@ -550,12 +550,12 @@ int PS4_SYSV_ABI sceUserServiceGetLoginFlag() {
     return ORBIS_OK;
 }
 
-s32 PS4_SYSV_ABI sceUserServiceGetLoginUserIdList(SceUserServiceLoginUserIdList* userIdList) {
+s32 PS4_SYSV_ABI sceUserServiceGetLoginUserIdList(OrbisUserServiceLoginUserIdList* userIdList) {
     PRINT_DUMMY_FUNCTION_NAME();
     userIdList->user_id[0] = 1;
-    userIdList->user_id[1] = -1;
-    userIdList->user_id[2] = -1;
-    userIdList->user_id[3] = -1;
+    userIdList->user_id[1] = ORBIS_USER_SERVICE_USER_ID_INVALID;
+    userIdList->user_id[2] = ORBIS_USER_SERVICE_USER_ID_INVALID;
+    userIdList->user_id[3] = ORBIS_USER_SERVICE_USER_ID_INVALID;
 
     return ORBIS_OK;
 }
@@ -1023,7 +1023,7 @@ int PS4_SYSV_ABI sceUserServiceGetTraditionalChineseInputType() {
 s32 PS4_SYSV_ABI sceUserServiceGetUserColor(int user_id, int* color) {
     // TODO fix me better
     PRINT_DUMMY_FUNCTION_NAME();
-    *color = 0; // blue
+    *color = ORBIS_USER_SERVICE_USER_COLOR_BLUE;
     return ORBIS_OK;
 }
 
@@ -1088,7 +1088,7 @@ int PS4_SYSV_ABI sceUserServiceGetVolumeForSidetone() {
     return ORBIS_OK;
 }
 
-s32 PS4_SYSV_ABI sceUserServiceInitialize(const SceUserServiceInitializeParams* initParams) {
+s32 PS4_SYSV_ABI sceUserServiceInitialize(const OrbisUserServiceInitializeParams* initParams) {
     PRINT_DUMMY_FUNCTION_NAME();
     return ORBIS_OK;
 }
diff --git a/src/core/libraries/libsceuserservice.h b/src/core/libraries/libsceuserservice.h
index e675e581..42213b9b 100644
--- a/src/core/libraries/libsceuserservice.h
+++ b/src/core/libraries/libsceuserservice.h
@@ -1,18 +1,56 @@
 // SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
-
+// reference :
+// https://github.com/OpenOrbis/OpenOrbis-PS4-Toolchain/blob/master/include/orbis/_types/user.h
 #pragma once
 
 #include "library_common.h"
 
 namespace Libraries::UserService {
 
-struct SceUserServiceInitializeParams {
+// Maximum number of users that can be logged in at once
+constexpr int ORBIS_USER_SERVICE_MAX_LOGIN_USERS = 4;
+// Maximum number of users that can be registered in the system
+constexpr int ORBIS_USER_SERVICE_MAX_REGISTER_USERS = 16;
+// Maximum user name length
+constexpr int ORBIS_USER_SERVICE_MAX_USER_NAME_LENGTH = 16;
+
+constexpr int ORBIS_USER_SERVICE_USER_ID_SYSTEM = 0xFF;
+constexpr int ORBIS_USER_SERVICE_USER_ID_INVALID = -1;
+
+using OrbisUserServiceUserId = s32;
+
+constexpr int ORBIS_KERNEL_PRIO_FIFO_LOWEST = 0x2FF;
+constexpr int ORBIS_KERNEL_PRIO_FIFO_NORMAL = 0x2BC;
+constexpr int ORBIS_KERNEL_PRIO_FIFO_HIGHEST = 0x100;
+
+struct OrbisUserServiceInitializeParams {
     s32 priority;
 };
 
-struct SceUserServiceLoginUserIdList {
-    int user_id[4];
+struct OrbisUserServiceLoginUserIdList {
+    int user_id[ORBIS_USER_SERVICE_MAX_LOGIN_USERS];
+};
+
+struct OrbisUserServiceRegisteredUserIdList {
+    OrbisUserServiceUserId userId[ORBIS_USER_SERVICE_MAX_REGISTER_USERS];
+};
+
+enum OrbisUserServiceUserColor : s32 {
+    ORBIS_USER_SERVICE_USER_COLOR_BLUE = 0,
+    ORBIS_USER_SERVICE_USER_COLOR_RED = 1,
+    ORBIS_USER_SERVICE_USER_COLOR_GREEN = 2,
+    ORBIS_USER_SERVICE_USER_COLOR_PINK = 3,
+};
+
+enum OrbisUserServiceEventType : s32 {
+    SCE_USER_SERVICE_EVENT_TYPE_LOGIN = 0,  // Login event
+    SCE_USER_SERVICE_EVENT_TYPE_LOGOUT = 1, // Logout event
+};
+
+struct OrbisUserServiceEvent {
+    OrbisUserServiceEventType event;
+    OrbisUserServiceUserId userId;
 };
 
 int PS4_SYSV_ABI sceUserServiceInitializeForShellCore();
@@ -123,7 +161,7 @@ int PS4_SYSV_ABI sceUserServiceGetKratosPrimaryUser();
 int PS4_SYSV_ABI sceUserServiceGetLastLoginOrder();
 int PS4_SYSV_ABI sceUserServiceGetLightBarBaseBrightness();
 int PS4_SYSV_ABI sceUserServiceGetLoginFlag();
-s32 PS4_SYSV_ABI sceUserServiceGetLoginUserIdList(SceUserServiceLoginUserIdList* userIdList);
+s32 PS4_SYSV_ABI sceUserServiceGetLoginUserIdList(OrbisUserServiceLoginUserIdList* userIdList);
 int PS4_SYSV_ABI sceUserServiceGetMicLevel();
 int PS4_SYSV_ABI sceUserServiceGetMouseHandType();
 int PS4_SYSV_ABI sceUserServiceGetMousePointerSpeed();
@@ -229,7 +267,7 @@ int PS4_SYSV_ABI sceUserServiceGetVolumeForController();
 int PS4_SYSV_ABI sceUserServiceGetVolumeForGenericUSB();
 int PS4_SYSV_ABI sceUserServiceGetVolumeForMorpheusSidetone();
 int PS4_SYSV_ABI sceUserServiceGetVolumeForSidetone();
-s32 PS4_SYSV_ABI sceUserServiceInitialize(const SceUserServiceInitializeParams* initParams);
+s32 PS4_SYSV_ABI sceUserServiceInitialize(const OrbisUserServiceInitializeParams* initParams);
 int PS4_SYSV_ABI sceUserServiceInitialize2();
 int PS4_SYSV_ABI sceUserServiceIsGuestUser();
 int PS4_SYSV_ABI sceUserServiceIsKratosPrimaryUser();