diff --git a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
index c34067e118..8380fd78be 100644
--- a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
+++ b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
@@ -235,6 +235,7 @@ GLOBAL_REMOVE_IF_UNREFERENCED EFI_LOAD_FIXED_ADDRESS_CONFIGURATION_TABLE    gLoa
 
 **/
 VOID
+NORETURN
 EFIAPI
 DxeMain (
   IN  VOID *HobStart
@@ -524,6 +525,8 @@ DxeMain (
   //
   ASSERT (FALSE);
   CpuDeadLoop ();
+
+  UNREACHABLE ();
 }
 
 
diff --git a/MdeModulePkg/Core/Pei/PeiMain.h b/MdeModulePkg/Core/Pei/PeiMain.h
index 24983201d0..54331dabd8 100644
--- a/MdeModulePkg/Core/Pei/PeiMain.h
+++ b/MdeModulePkg/Core/Pei/PeiMain.h
@@ -315,6 +315,7 @@ typedef struct {
 
 **/
 VOID
+NORETURN
 EFIAPI
 PeiCore (
   IN CONST EFI_SEC_PEI_HAND_OFF        *SecCoreData,
diff --git a/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c b/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c
index 10db496140..59fdd2614b 100644
--- a/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c
+++ b/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c
@@ -136,6 +136,7 @@ ShadowPeiCore (
 
 **/
 VOID
+NORETURN
 EFIAPI
 PeiCore (
   IN CONST EFI_SEC_PEI_HAND_OFF        *SecCoreDataPtr,
@@ -275,6 +276,8 @@ PeiCore (
       //
       ASSERT (FALSE);
       CpuDeadLoop();
+
+      UNREACHABLE ();
     }
 
     //
@@ -468,4 +471,6 @@ PeiCore (
   //
   ASSERT_EFI_ERROR (Status);
   CpuDeadLoop();
+
+  UNREACHABLE ();
 }