diff --git a/library/apply.yap b/library/apply.yap
index a4c18cca9..6d2fe8248 100644
--- a/library/apply.yap
+++ b/library/apply.yap
@@ -1,4 +1,6 @@
 
+:- module(apply,[]).
+
 :- reexport(library(apply_macros),
 	    [maplist/3,
 	     include/3,
diff --git a/library/expand_macros.yap b/library/expand_macros.yap
index b3838c981..ea8efe8ee 100644
--- a/library/expand_macros.yap
+++ b/library/expand_macros.yap
@@ -5,6 +5,8 @@
 %%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
+:- module(expand_macros, []).
+
 :- use_module(library(lists), [append/3]).
 :- use_module(library(charsio), [format_to_chars/3, read_from_chars/2]).
 :- use_module(library(error), [must_be/2]).
@@ -394,6 +396,7 @@ user:goal_expansion(sumnodes(Meta, Term, AccIn, AccOut), Mod, Goal) :-
 			 ),
 			 RecursiveCall)
 		    ], Module).
+
 :- unhide('$translate_rule').
 % stolen from SWI-Prolog
 user:goal_expansion(phrase(NT,Xs), Mod, NTXsNil) :-
diff --git a/library/lists.yap b/library/lists.yap
index c7c44d58d..5ae141522 100644
--- a/library/lists.yap
+++ b/library/lists.yap
@@ -38,7 +38,8 @@
 	   numlist/3
 	  ]).
 
-:- ensure_loaded(library(error)).
+:- ensure_loaded(library(error),
+		 [must_be/2]).
 
 
 %   append(Prefix, Suffix, Combined)
diff --git a/library/undgraphs.yap b/library/undgraphs.yap
index 3b62228f3..b9c269ad0 100644
--- a/library/undgraphs.yap
+++ b/library/undgraphs.yap
@@ -5,7 +5,6 @@
 
 :- module( undgraphs,
 	   [
-	    undgraph_new/1,
 	    undgraph_add_edge/4,
 	    undgraph_add_edges/3,
 	    undgraph_add_vertices/3,
@@ -13,13 +12,10 @@
 	    undgraph_del_edges/3,
 	    undgraph_del_vertex/3,
 	    undgraph_del_vertices/3,
-	    undgraph_edge/3,
 	    undgraph_edges/2,
 	    undgraph_neighbors/3,
 	    undgraph_neighbours/3,
-	    undgraph_complement/2,
 	    undgraph_components/2,
-	    dgraph_to_undgraph/2,
 	    undgraph_min_tree/2]).
 
 :- reexport( library(dgraphs),
@@ -60,6 +56,7 @@
 
 :- use_module(library(rbtrees),
 	[  rb_delete/4,
+	   rb_delete/3,
 	   rb_insert/4,
 	   rb_in/3,
 	   rb_partial_map/4
diff --git a/library/wundgraphs.yap b/library/wundgraphs.yap
index 3462d1512..10f07f032 100644
--- a/library/wundgraphs.yap
+++ b/library/wundgraphs.yap
@@ -15,8 +15,6 @@
 	    wundgraph_neighbours/3,
 	    wundgraph_wneighbors/3,
 	    wundgraph_wneighbours/3,
-	    wdgraph_to_wundgraph/2,
-	    wundgraph_to_undgraph/2,
 	    wundgraph_min_tree/3,
 	    wundgraph_max_tree/3]).
 
@@ -46,7 +44,8 @@
 	    wdgraph_del_edges/3,
 	    wdgraph_del_vertex/3,
 	    wdgraph_edges/2,
-	    wdgraph_neighbors/3,
+	    wdgraph_neighbours/3,
+	    wdgraph_wneighbours/3,
 	    wdgraph_symmetric_closure/2
 	   ]).
 
@@ -98,7 +97,7 @@ wundgraph_neighbours(V,Vertices,Children) :-
 	    Children = Children0
 	).
 wundgraph_neighbors(V,Vertices,Children) :-
-	wdgraph_neighbors(V,Vertices,Children0),
+	wdgraph_neighbours(V,Vertices,Children0),
 	(
 	    wdel_me(Children0,V,Children)
 	->
@@ -117,7 +116,7 @@ wundgraph_wneighbours(V,Vertices,Children) :-
 	    Children = Children0
 	).
 wundgraph_wneighbors(V,Vertices,Children) :-
-	wdgraph_wneighbors(V,Vertices,Children0),
+	wdgraph_wneighbours(V,Vertices,Children0),
 	(
 	    del_me(Children0,V,Children)
 	->