diff --git a/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm b/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
index e8468a3fbf..e3d0d4e417 100644
--- a/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
+++ b/MdePkg/Library/BaseLib/Ia32/Thunk16.nasm
@@ -85,7 +85,11 @@ _BackFromUserCode:
 BITS    16
     push    ss
     push    cs
-o32 call    dword .Base                 ; push eip
+    ;
+    ; Note: We can't use o32 on the next instruction because of a bug
+    ; in NASM 2.09.04 through 2.10rc1.
+    ;
+    call    dword .Base                 ; push eip
 .Base:
     pushfd
     cli                                 ; disable interrupts
diff --git a/MdePkg/Library/BaseLib/X64/Thunk16.nasm b/MdePkg/Library/BaseLib/X64/Thunk16.nasm
index 6084fac8c4..7c4a8d3e17 100644
--- a/MdePkg/Library/BaseLib/X64/Thunk16.nasm
+++ b/MdePkg/Library/BaseLib/X64/Thunk16.nasm
@@ -83,7 +83,11 @@ _BackFromUserCode:
 BITS    16
     push    ss
     push    cs
-o32 call    dword .Base                 ; push eip
+    ;
+    ; Note: We can't use o32 on the next instruction because of a bug
+    ; in NASM 2.09.04 through 2.10rc1.
+    ;
+    call    dword .Base                 ; push eip
 .Base:
     push    dword 0                     ; reserved high order 32 bits of EFlags
     pushfd