diff --git a/EdkNt32Pkg/Include/Protocol/WinNtThunk.h b/EdkNt32Pkg/Include/Protocol/WinNtThunk.h
index 6ebc93fb6f..b3e161f7cd 100644
--- a/EdkNt32Pkg/Include/Protocol/WinNtThunk.h
+++ b/EdkNt32Pkg/Include/Protocol/WinNtThunk.h
@@ -790,6 +790,7 @@ WINUSERAPI
 INT32
 (WINAPIV *WinNtSprintf) (
   LPWSTR    Buffer,
+  size_t    Count,
   LPCWSTR   String,
   ...
   );