Unset Strict Universe Declaration. Set Universe Polymorphism. Set Printing Universes. Record Cat := { Obj :> Type }. Definition set_cat := {| Obj := Type |}. Goal Type@{i} = Type@{j}. Proof. (* 1 subgoals , subgoal 1 (ID 3) ============================ Type@{Top.368} = Type@{Top.370} (dependent evars:) *) Fail change Type@{i} with (Obj set_cat@{i}). (* check that it fails *) try change Type@{i} with (Obj set_cat@{i}). (* check that it's not an anomaly *) (* Anomaly: Uncaught exception Invalid_argument("Array.iter2", _). Please report. *)