diff --git a/reactos/ntoskrnl/se/sd.c b/reactos/ntoskrnl/se/sd.c
index 3d27f6910f9..5ebccb6bac3 100644
--- a/reactos/ntoskrnl/se/sd.c
+++ b/reactos/ntoskrnl/se/sd.c
@@ -237,7 +237,7 @@ SepCaptureSecurityQualityOfService(IN POBJECT_ATTRIBUTES ObjectAttributes  OPTIO
       _SEH_TRY
       {
         ProbeForRead(ObjectAttributes,
-                     sizeof(ObjectAttributes),
+                     sizeof(OBJECT_ATTRIBUTES),
                      sizeof(ULONG));
         if(ObjectAttributes->Length == sizeof(OBJECT_ATTRIBUTES))
         {