diff --git a/pl/error.yap b/pl/error.yap
index 08e8a4bea..49a5188a5 100644
--- a/pl/error.yap
+++ b/pl/error.yap
@@ -108,6 +108,9 @@ must_be_of_type(callable, X) :-
 must_be_of_type(atom, X) :-
 	!,
 	is_atom(X, _).
+must_be_of_type(module, X) :-
+	!,
+	is_atom(X, _).
 must_be_of_type(predicate_indicator, X) :-
 	!,
 	is_predicate_indicator(X, _).
@@ -117,8 +120,12 @@ must_be_of_type(Type, X) :-
 	;   is_not(Type, X)
 	).
 
+inline(must_be_of_type( atom, X ), is_atom(X, _) ).
+inline(must_be_of_type( module, X ), is_module(X, _) ).
 inline(must_be_of_type( callable, X ), is_callable(X, _) ).
 inline(must_be_of_type( callable, X ), is_callable(X, _) ).
+inline(must_be_atom( X ), is_callable(X, _) ).
+inline(must_be_module( X ), is_atom(X, _) ).
 
 must_be_of_type(predicate_indicator, X, Comment) :-
 	!,