1 files changed, 3 insertions, 0 deletions
diff --git a/src/class.c b/src/class.c
index d120f1fec..bac1d2984 100644
--- a/src/class.c
+++ b/src/class.c
@@ -1348,6 +1348,9 @@ mrb_instance_alloc(mrb_state *mrb, mrb_value cv)
     mrb_raise(mrb, E_TYPE_ERROR, "can't create instance of singleton class");
 
   if (ttype == 0) ttype = MRB_TT_OBJECT;
+  if (ttype <= MRB_TT_CPTR) {
+    mrb_raisef(mrb, E_TYPE_ERROR, "can't create instance of %S", cv);
+  }
   o = (struct RObject*)mrb_obj_alloc(mrb, ttype, c);
   return mrb_obj_value(o);
 }