diff --git a/include/ntddk.h b/include/ntddk.h
index 071c109d955..a8256e7cc29 100644
--- a/include/ntddk.h
+++ b/include/ntddk.h
@@ -760,6 +760,7 @@ DWORD WINAPI RtlIsTextUnicode(
 	DWORD *pf);
 
 INT __cdecl wcstol(LPCWSTR,LPWSTR*,INT);
+int __cdecl swprintf(LPWSTR,LPCWSTR,...);
 
 /*	resource functions */