diff --git a/pd/extra/expr~/vexp_if.c b/pd/extra/expr~/vexp_if.c
index a3499f4563e87da0a802e217ad93b81983ff246e..f8c7571207200c94cf6e5b4821315caa3410b4aa 100644
--- a/pd/extra/expr~/vexp_if.c
+++ b/pd/extra/expr~/vexp_if.c
@@ -281,7 +281,7 @@ Nexpr_new(t_symbol *s, int ac, t_atom *av)
                 x = (t_expr *)pd_new(fexpr_tilde_class);
                 SET_FEXPR_TILDE(x);
         } else {
-                post("expr_new: bad object name '%s'");
+                post("expr_new: bad object name '%s'", s->s_name);
                 /* assume expr */
                 x = (t_expr *)pd_new(expr_class);
                 SET_EXPR(x);