diff --git a/reactos/dll/win32/advapi32/service/sctrl.c b/reactos/dll/win32/advapi32/service/sctrl.c
index abfe4269a45..cab423849e3 100644
--- a/reactos/dll/win32/advapi32/service/sctrl.c
+++ b/reactos/dll/win32/advapi32/service/sctrl.c
@@ -177,7 +177,7 @@ ScServiceMainStub(LPVOID Context)
         (lpService->ThreadParams.W.lpServiceMain)(lpService->ThreadParams.W.dwArgCount,
                                                   lpService->ThreadParams.W.lpArgVector);
 
-        if (lpService->ThreadParams.A.lpArgVector != NULL)
+        if (lpService->ThreadParams.W.lpArgVector != NULL)
         {
             HeapFree(GetProcessHeap(),
                      0,