diff --git a/reactos/base/system/winlogon/sas.c b/reactos/base/system/winlogon/sas.c
index dfbe97eee29..7e71ed1691e 100644
--- a/reactos/base/system/winlogon/sas.c
+++ b/reactos/base/system/winlogon/sas.c
@@ -1174,6 +1174,11 @@ SASWindowProc(
                     inScrn = FALSE;
                     break;
                 }
+                case LN_LOCK_WORKSTATION:
+                {
+                    DoGenericAction(Session, WLX_SAS_ACTION_LOCK_WKSTA);
+                    break;
+                }
                 default:
                 {
                     ERR("WM_LOGONNOTIFY case %d is unimplemented\n", wParam);
diff --git a/reactos/win32ss/user/ntuser/ntstubs.c b/reactos/win32ss/user/ntuser/ntstubs.c
index 17418c8aa5d..7ff8e8af5cc 100644
--- a/reactos/win32ss/user/ntuser/ntstubs.c
+++ b/reactos/win32ss/user/ntuser/ntstubs.c
@@ -307,15 +307,6 @@ NtUserInitTask(
    return 0;
 }
 
-BOOL
-APIENTRY
-NtUserLockWorkStation(VOID)
-{
-   STUB
-
-   return 0;
-}
-
 DWORD
 APIENTRY
 NtUserMNDragLeave(VOID)
diff --git a/reactos/win32ss/user/ntuser/winsta.c b/reactos/win32ss/user/ntuser/winsta.c
index 1f174ba73a4..3056fc3d5bf 100644
--- a/reactos/win32ss/user/ntuser/winsta.c
+++ b/reactos/win32ss/user/ntuser/winsta.c
@@ -1320,4 +1320,27 @@ NtUserSetLogonNotifyWindow(HWND hWnd)
     return TRUE;
 }
 
+BOOL
+APIENTRY
+NtUserLockWorkStation(VOID)
+{
+    BOOL ret;
+    PTHREADINFO pti = PsGetCurrentThreadWin32Thread();
+
+    UserEnterExclusive();
+
+    if (pti->rpdesk == IntGetActiveDesktop())
+    {
+        ret = UserPostMessage(hwndSAS, WM_LOGONNOTIFY, LN_LOCK_WORKSTATION, 0);
+    }
+    else
+    {
+        ret = FALSE;
+    }
+
+    UserLeave();
+
+   return ret;
+}
+
 /* EOF */