diff --git a/src/lib/freeze.pl b/src/lib/freeze.pl
index 8ab1de9b..c005672f 100644
--- a/src/lib/freeze.pl
+++ b/src/lib/freeze.pl
@@ -3,6 +3,8 @@
 :- use_module(library(atts)).
 :- use_module(library(dcgs)).
 
+:- meta_predicate freeze(?, 0).
+
 :- attribute frozen/1.
 
 verify_attributes(Var, Other, Goals) :-
diff --git a/src/lib/pio.pl b/src/lib/pio.pl
index 89dfc566..1df9a796 100644
--- a/src/lib/pio.pl
+++ b/src/lib/pio.pl
@@ -7,6 +7,9 @@
 :- use_module(library(iso_ext), [setup_call_cleanup/3, partial_string/3]).
 :- use_module(library(lists), [member/2]).
 
+:- meta_predicate phrase_from_file(2, ?).
+:- meta_predicate phrase_from_file(2, ?, ?).
+
 phrase_from_file(NT, File) :-
     phrase_from_file(NT, File, []).