diff --git a/MdePkg/Library/BaseLib/X64/SetJump.asm b/MdePkg/Library/BaseLib/X64/SetJump.asm
index efdbb9a1fc..13cb323fc0 100644
--- a/MdePkg/Library/BaseLib/X64/SetJump.asm
+++ b/MdePkg/Library/BaseLib/X64/SetJump.asm
@@ -21,7 +21,7 @@
 
     .code
 
-EXTERNDEF   InternalAssertJumpBuffer:PROC
+EXTERN   InternalAssertJumpBuffer:PROC
 
 ;------------------------------------------------------------------------------
 ; UINTN