diff --git a/dlls/oleaut32/tests/vartest.c b/dlls/oleaut32/tests/vartest.c
index 127af46ba19..8492a720855 100644
--- a/dlls/oleaut32/tests/vartest.c
+++ b/dlls/oleaut32/tests/vartest.c
@@ -26,6 +26,7 @@
 
 #define COBJMACROS
 #define CONST_VTABLE
+#define NONAMELESSUNION
 
 #include "windef.h"
 #include "winbase.h"