1 files changed, 2 insertions, 2 deletions
diff --git a/marshal.c b/marshal.c
index 1fae54530a..b38c53c05c 100644
--- a/marshal.c
+++ b/marshal.c
@@ -904,8 +904,8 @@ w_object(VALUE obj, struct dump_arg *arg, int limit)
 	    break;
 
 	  default:
-	    rb_raise(rb_eTypeError, "can't dump %s",
-		     rb_obj_classname(obj));
+	    rb_raise(rb_eTypeError, "can't dump %"PRIsVALUE,
+		     rb_obj_class(obj));
 	    break;
 	}
 	RB_GC_GUARD(obj);