Fix incorrect usage of COBJMACROS.
diff --git a/include/mapiutil.h b/include/mapiutil.h
index 86983b5..4f6d147 100644
--- a/include/mapiutil.h
+++ b/include/mapiutil.h
@@ -139,7 +139,7 @@
DECLARE_INTERFACE_(ITableData,IUnknown) { ITableData_METHODS };
#undef INTERFACE
-#ifdef COBJMACROS
+#if !defined(__cplusplus) || defined(CINTERFACE)
/*** IUnknown methods ***/
#define ITableData_QueryInterface(p,a,b) (p)->lpVtbl->QueryInterface(p,a,b)
#define ITableData_AddRef(p) (p)->lpVtbl->AddRef(p)
@@ -223,7 +223,7 @@
DECLARE_INTERFACE_(IPropData,IMAPIProp) { IPropData_METHODS };
#undef INTERFACE
-#ifdef COBJMACROS
+#if !defined(__cplusplus) || defined(CINTERFACE)
/*** IUnknown methods ***/
#define IPropData_QueryInterface(p,a,b) (p)->lpVtbl->QueryInterface(p,a,b)
#define IPropData_AddRef(p) (p)->lpVtbl->AddRef(p)