diff --git a/reactos/include/ndk/pstypes.h b/reactos/include/ndk/pstypes.h
index 9033b78e5b4..ad7e9dd196c 100644
--- a/reactos/include/ndk/pstypes.h
+++ b/reactos/include/ndk/pstypes.h
@@ -575,13 +575,17 @@ typedef struct _PEB
     UCHAR InheritedAddressSpace;
     UCHAR ReadImageFileExecOptions;
     UCHAR BeingDebugged;
-#if (NTDDI_VERSION >= NTDDI_LONGHORN)
+#if (NTDDI_VERSION >= NTDDI_WS03)
     struct
     {
         UCHAR ImageUsesLargePages:1;
+    #if (NTDDI_VERSION >= NTDDI_LONGHORN)
         UCHAR IsProtectedProcess:1;
         UCHAR IsLegacyProcess:1;
         UCHAR SpareBits:5;
+    #else
+        UCHAR SpareBits:7;
+    #endif
     };
 #else
     BOOLEAN SpareBool;