diff --git a/MdeModulePkg/Include/Pi/PrePiDxeCis.h b/MdeModulePkg/Include/Pi/PrePiDxeCis.h
index 113ac37924..9be71d2618 100644
--- a/MdeModulePkg/Include/Pi/PrePiDxeCis.h
+++ b/MdeModulePkg/Include/Pi/PrePiDxeCis.h
@@ -20,6 +20,6 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 /// After this memory region is defined in PI spec, it should be a value in
 /// EFI_GCD_MEMORY_TYPE in PiDxeCis.h.
 ///
-#define  EFI_GCD_MEMORY_TYPE_UNACCEPTED  7
+#define  EFI_GCD_MEMORY_TYPE_UNACCEPTED  6
 
 #endif
diff --git a/MdePkg/Include/Pi/PiDxeCis.h b/MdePkg/Include/Pi/PiDxeCis.h
index 27b219aa3f..bb7fb2c38a 100644
--- a/MdePkg/Include/Pi/PiDxeCis.h
+++ b/MdePkg/Include/Pi/PiDxeCis.h
@@ -64,7 +64,7 @@ typedef enum {
   // /// EfiGcdMemoryTypeUnaccepted is defined in PrePiDxeCis.h because it has not been
   // /// defined in PI spec.
   // EfiGcdMemoryTypeUnaccepted,
-  EfiGcdMemoryTypeMaximum = 8
+  EfiGcdMemoryTypeMaximum = 7
 } EFI_GCD_MEMORY_TYPE;
 
 ///