diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmFuncsArch.c b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmFuncsArch.c
index 6c48a53f67..636dc8d92f 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmFuncsArch.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmFuncsArch.c
@@ -1,7 +1,7 @@
 /** @file
   SMM CPU misc functions for Ia32 arch specific.
 
-Copyright (c) 2015 - 2019, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2015 - 2023, Intel Corporation. All rights reserved.<BR>
 SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -14,7 +14,6 @@ EFI_PHYSICAL_ADDRESS  mGdtBuffer;
 UINTN                 mGdtBufferSize;
 
 extern BOOLEAN  mCetSupported;
-extern UINTN    mSmmShadowStackSize;
 
 X86_ASSEMBLY_PATCH_LABEL  mPatchCetPl0Ssp;
 X86_ASSEMBLY_PATCH_LABEL  mPatchCetInterruptSsp;
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index 8364b73242..8c61d68afd 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -29,8 +29,6 @@ MM_COMPLETION                mSmmStartupThisApToken;
 //
 UINT32  *mPackageFirstThreadIndex = NULL;
 
-extern UINTN  mSmmShadowStackSize;
-
 /**
   Performs an atomic compare exchange operation to get semaphore.
   The compare exchange operation must be performed using
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
index c912e9f0e3..7326c13d01 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
@@ -264,6 +264,7 @@ extern EFI_SMM_CPU_PROTOCOL  mSmmCpu;
 extern EFI_MM_MP_PROTOCOL    mSmmMp;
 extern BOOLEAN               m5LevelPagingNeeded;
 extern PAGING_MODE           mPagingMode;
+extern UINTN                 mSmmShadowStackSize;
 
 ///
 /// The mode of the CPU at the time an SMI occurs
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
index 0bed857cae..46d8ff5d4e 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
@@ -13,8 +13,6 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 #define PAGE_TABLE_PAGES  8
 #define ACC_MAX_BIT       BIT3
 
-extern UINTN  mSmmShadowStackSize;
-
 LIST_ENTRY                mPagePool           = INITIALIZE_LIST_HEAD_VARIABLE (mPagePool);
 BOOLEAN                   m1GPageTableSupport = FALSE;
 BOOLEAN                   mCpuSmmRestrictedMemoryAccess;
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmFuncsArch.c b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmFuncsArch.c
index 00a284c369..c4f21e2155 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmFuncsArch.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmFuncsArch.c
@@ -1,7 +1,7 @@
 /** @file
   SMM CPU misc functions for x64 arch specific.
 
-Copyright (c) 2015 - 2019, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2015 - 2023, Intel Corporation. All rights reserved.<BR>
 SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -12,7 +12,6 @@ EFI_PHYSICAL_ADDRESS  mGdtBuffer;
 UINTN                 mGdtBufferSize;
 
 extern BOOLEAN  mCetSupported;
-extern UINTN    mSmmShadowStackSize;
 
 X86_ASSEMBLY_PATCH_LABEL  mPatchCetPl0Ssp;
 X86_ASSEMBLY_PATCH_LABEL  mPatchCetInterruptSsp;