diff --git a/lib/std/os/windows/ole32.zig b/lib/std/os/windows/ole32.zig
index f46ee33047..b3048873d0 100644
--- a/lib/std/os/windows/ole32.zig
+++ b/lib/std/os/windows/ole32.zig
@@ -8,4 +8,4 @@ usingnamespace @import("bits.zig");
 pub extern "ole32" fn CoTaskMemFree(pv: LPVOID) callconv(.Stdcall) void;
 pub extern "ole32" fn CoUninitialize() callconv(.Stdcall) void;
 pub extern "ole32" fn CoGetCurrentProcess() callconv(.Stdcall) DWORD;
-pub extern "ole32" fn CoInitializeEx(pvReserved: LPVOID, dwCoInit: DWORD) callconv(.Stdcall) HRESULT;
+pub extern "ole32" fn CoInitializeEx(pvReserved: ?LPVOID, dwCoInit: DWORD) callconv(.Stdcall) HRESULT;