diff --git a/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm b/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
index c08e41de9d..e8468a3fbf 100644
--- a/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
+++ b/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
@@ -139,7 +139,7 @@ _16Idtr:
 _16Gdtr:
         DW      GdtEnd - _NullSegDesc - 1
 _16GdtrBase:
-        DD      _NullSegDesc
+        DD      0
 
 ;------------------------------------------------------------------------------
 ; _ToUserCode() takes control in real mode before passing control to user code.
diff --git a/MdePkg/Library/BaseLib/X64/Thunk16.nasm b/MdePkg/Library/BaseLib/X64/Thunk16.nasm
index d15984b01c..6084fac8c4 100644
--- a/MdePkg/Library/BaseLib/X64/Thunk16.nasm
+++ b/MdePkg/Library/BaseLib/X64/Thunk16.nasm
@@ -145,7 +145,7 @@ _EntryPoint:
 _16Gdtr:
         DW      GDT_SIZE - 1
 _16GdtrBase:
-        DQ      _NullSeg
+        DQ      0
 _16Idtr:
         DW      (1 << 10) - 1
         DD      0