diff --git a/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EdkiiPeiMpServices2PpiUnitTest.c b/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EdkiiPeiMpServices2PpiUnitTest.c
index 5c42a81d29..328e99cbda 100644
--- a/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EdkiiPeiMpServices2PpiUnitTest.c
+++ b/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EdkiiPeiMpServices2PpiUnitTest.c
@@ -215,6 +215,7 @@ MpServicesUnitTestStartupAllCPUs (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 ApInfiniteLoopProcedure (
   IN OUT VOID  *Buffer
   )
@@ -245,6 +246,7 @@ ApInfiniteLoopProcedure (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 RunMpServiceStartupAllCPUsOnAp (
   IN OUT VOID  *Buffer
   )
diff --git a/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EfiMpServicesUnitTestCommom.c b/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EfiMpServicesUnitTestCommom.c
index 7cd3f48d76..d7fa06c992 100644
--- a/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EfiMpServicesUnitTestCommom.c
+++ b/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EfiMpServicesUnitTestCommom.c
@@ -231,6 +231,7 @@ FreeUTContext (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 StoreCpuNumbers (
   IN OUT VOID  *Buffer
   )
@@ -260,6 +261,7 @@ StoreCpuNumbers (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 StoreAPsExecutionOrder (
   IN OUT VOID  *Buffer
   )
@@ -290,6 +292,7 @@ StoreAPsExecutionOrder (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 InfiniteLoopProcedure (
   IN OUT VOID  *Buffer
   )
@@ -308,6 +311,7 @@ InfiniteLoopProcedure (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 EmptyProcedure (
   IN OUT VOID  *Buffer
   )
@@ -320,6 +324,7 @@ EmptyProcedure (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 RunMpServiceGetNumberOfProcessorsOnAp (
   IN OUT VOID  *Buffer
   )
@@ -343,6 +348,7 @@ RunMpServiceGetNumberOfProcessorsOnAp (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 RunMpServiceGetProcessorInfoOnAp (
   IN OUT VOID  *Buffer
   )
@@ -365,6 +371,7 @@ RunMpServiceGetProcessorInfoOnAp (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 RunMpServiceEnableDisableAPOnAp (
   IN OUT VOID  *Buffer
   )
@@ -387,6 +394,7 @@ RunMpServiceEnableDisableAPOnAp (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 RunMpServiceStartupThisAPOnAp (
   IN OUT VOID  *Buffer
   )
@@ -410,6 +418,7 @@ RunMpServiceStartupThisAPOnAp (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 RunMpServiceStartupAllAPsOnAp (
   IN OUT VOID  *Buffer
   )
@@ -433,6 +442,7 @@ RunMpServiceStartupAllAPsOnAp (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 RunMpServiceSwitchBSPOnAp (
   IN OUT VOID  *Buffer
   )
diff --git a/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EfiMpServicesUnitTestCommom.h b/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EfiMpServicesUnitTestCommom.h
index d2b1633b4d..2df400009c 100644
--- a/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EfiMpServicesUnitTestCommom.h
+++ b/UefiCpuPkg/Test/UnitTest/EfiMpServicesPpiProtocol/EfiMpServicesUnitTestCommom.h
@@ -191,6 +191,7 @@ MpServicesUnitTestWhoAmI (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 EmptyProcedure (
   IN OUT VOID  *Buffer
   );
@@ -201,6 +202,7 @@ EmptyProcedure (
   @param[in,out] Buffer   The pointer to private data buffer.
 **/
 VOID
+EFIAPI
 StoreCpuNumbers (
   IN OUT VOID  *Buffer
   );