diff --git a/tools/widl/parser.y b/tools/widl/parser.y
index 5d99c5a70fc..cc5aca52b83 100644
--- a/tools/widl/parser.y
+++ b/tools/widl/parser.y
@@ -1017,6 +1017,7 @@ static expr_t *make_expr(enum expr_type type)
   e->ref = NULL;
   e->u.lval = 0;
   e->is_const = FALSE;
+  e->cval = 0;
   return e;
 }