diff --git a/tools/widl/header.c b/tools/widl/header.c
index 5ab8a3cc26f..e1dcab9b75b 100644
--- a/tools/widl/header.c
+++ b/tools/widl/header.c
@@ -1482,6 +1482,8 @@ static void write_forward(FILE *header, type_t *iface)
   fprintf(header, "#define __%s_FWD_DEFINED__\n", iface->c_name);
   fprintf(header, "typedef interface %s %s;\n", iface->c_name, iface->c_name);
   fprintf(header, "#ifdef __cplusplus\n");
+  if (iface->namespace && !is_global_namespace(iface->namespace))
+    fprintf(header, "#define %s %s\n", iface->c_name, iface->qualified_name);
   write_namespace_start(header, iface->namespace);
   if (strchr(iface->name, '<')) write_line(header, 0, "template<> struct %s;", iface->name);
   else write_line(header, 0, "interface %s;", iface->name);