diff --git a/MdeModulePkg/Include/Pi/PrePiHob.h b/MdeModulePkg/Include/Pi/PrePiHob.h
new file mode 100644
index 0000000000..ac575e5972
--- /dev/null
+++ b/MdeModulePkg/Include/Pi/PrePiHob.h
@@ -0,0 +1,20 @@
+/** @file
+  HOB related definitions which has not been officially published in PI.
+
+Copyright (c) 2022, Intel Corporation. All rights reserved.<BR>
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef MDE_MODULEPKG_PRE_PI_HOB_H_
+#define MDE_MODULEPKG_PRE_PI_HOB_H_
+
+//
+// BZ3937_EFI_RESOURCE_MEMORY_UNACCEPTED is defined for unaccepted memory.
+// But this defitinion has not been officially in the PI spec. Base
+// on the code-first we define BZ3937_EFI_RESOURCE_MEMORY_UNACCEPTED at
+// MdeModulePkg/Include/Pi/PrePiHob.h.
+//
+#define BZ3937_EFI_RESOURCE_MEMORY_UNACCEPTED  0x00000007
+
+#endif