diff --git a/packages/ProbLog/problog.yap b/packages/ProbLog/problog.yap
index a6c576ad0..fd8920c07 100644
--- a/packages/ProbLog/problog.yap
+++ b/packages/ProbLog/problog.yap
@@ -304,10 +304,10 @@
 :- use_module(library(charsio)).
 :- use_module(library(lists)).
 :- use_module(library(terms)).
-:- use_module(library(random)).
+:- use_module(library(random)).		% PM doesn't seem to be used!
 :- use_module(library(system)).
-:- use_module(library(rbtrees)).
-:- use_module(library(ordsets)).
+:- use_module(library(rbtrees)).	% PM doesn't seem to be used!
+:- use_module(library(ordsets), [list_to_ord_set/2, ord_insert/3, ord_union/3]).
 
 % problog related modules
 :- use_module('problog/variables').
diff --git a/packages/ProbLog/problog_learning.yap b/packages/ProbLog/problog_learning.yap
index 8f1ab70a0..8b406f3e3 100644
--- a/packages/ProbLog/problog_learning.yap
+++ b/packages/ProbLog/problog_learning.yap
@@ -223,9 +223,9 @@
 :- yap_flag(unknown,error).
 
 % load modules from the YAP library
-:- use_module(library(lists)).
-:- use_module(library(random)).
-:- use_module(library(system)).
+:- use_module(library(lists), [max_list/2, min_list/2, sum_list/2]).
+:- use_module(library(random)).	% PM doesn't seem to be used!
+:- use_module(library(system), [delete_file/1, file_exists/1, shell/2]).
 
 % load our own modules
 :- use_module(problog).