diff --git a/reactos/include/psdk/winuser.h b/reactos/include/psdk/winuser.h
index 15ee3b0a678..1bdd90b4010 100644
--- a/reactos/include/psdk/winuser.h
+++ b/reactos/include/psdk/winuser.h
@@ -4365,6 +4365,9 @@ ATOM WINAPI RegisterClassA(CONST WNDCLASSA*);
 ATOM WINAPI RegisterClassW(CONST WNDCLASSW*);
 ATOM WINAPI RegisterClassExA(CONST WNDCLASSEXA*);
 ATOM WINAPI RegisterClassExW(CONST WNDCLASSEXW*);
+#if(_WIN32_WINNT >= 0x0501)
+typedef BOOLEAN (WINAPI * PREGISTERCLASSNAMEW)(LPCWSTR);
+#endif
 UINT WINAPI RegisterClipboardFormatA(LPCSTR);
 UINT WINAPI RegisterClipboardFormatW(LPCWSTR);
 #if (WINVER >= 0x0500)