diff --git a/src/multimedia/windows/qwindows_propertystore.cpp b/src/multimedia/windows/qwindows_propertystore.cpp
index 1234567..abcdef0 100644
--- a/src/multimedia/windows/qwindows_propertystore.cpp
+++ b/src/multimedia/windows/qwindows_propertystore.cpp
@@ -71,10 +71,21 @@ template <typename T>
 template <typename T>
 struct first_arg_is_ptr;
 
 // Function type
 template <typename Result, typename Arg, typename... Args>
 struct first_arg_is_ptr<Result (*)(Arg, Args...)> : std::bool_constant<std::is_pointer_v<Arg>>
 {
 };
 
+// On MSVC x86, __stdcall is a distinct calling convention from __cdecl.
+// The specialization above only matches __cdecl function pointers, so we need
+// an additional specialization for __stdcall (used by Win32 API functions like
+// PropVariantToGUID on 32-bit Windows).
+#if defined(_MSC_VER) && defined(_M_IX86)
+template <typename Result, typename Arg, typename... Args>
+struct first_arg_is_ptr<Result (__stdcall *)(Arg, Args...)> : std::bool_constant<std::is_pointer_v<Arg>>
+{
+};
+#endif
+
 auto wrapPropVariantArg(const PROPVARIANT &arg)