diff --git a/tools/widl/parser.y b/tools/widl/parser.y
index 745056f1b7a..eb9b2c9fd45 100644
--- a/tools/widl/parser.y
+++ b/tools/widl/parser.y
@@ -845,7 +845,7 @@ uniondef: tUNION t_ident '{' fields '}'		{ $$ = get_typev(RPC_FC_NON_ENCAPSULATE
 	  m_ident '{' cases '}'			{ var_t *u = $7;
 						  $$ = get_typev(RPC_FC_ENCAPSULATED_UNION, $2, tsUNION);
 						  $$->kind = TKIND_UNION;
-						  if (!u) u = make_var("tagged_union");
+						  if (!u) u = make_var( xstrdup("tagged_union") );
 						  u->type = make_type(RPC_FC_NON_ENCAPSULATED_UNION, NULL);
 						  u->type->kind = TKIND_UNION;
 						  u->type->fields = $9;