diff --git a/CLPBN/clpbn/evidence.yap b/CLPBN/clpbn/evidence.yap
index 05fe50b7c..93b361882 100644
--- a/CLPBN/clpbn/evidence.yap
+++ b/CLPBN/clpbn/evidence.yap
@@ -25,9 +25,9 @@
 :- dynamic node/4, reachable_from_evidence/2, evidence/2.
 
 %
-% new evidence storagea algorithm. The idea is that instead of 
+% new evidence storage algorithm. The idea is that instead of 
 % redoing all the evidence every time we query the network, we shall
-% keep a precompiled version around. The precompiled
+% keep a precompiled version around.
 %
 % the format is as follows:
 %  evidence_store:parent(Key,ParentList,[EvidenceChildren])
diff --git a/pl/debug.yap b/pl/debug.yap
index db2c2593a..8a6aba3b3 100644
--- a/pl/debug.yap
+++ b/pl/debug.yap
@@ -459,15 +459,14 @@ debugging :-
 '$action'(10,_,_,_,_) :- 			% newline 	creep
 	( recorded('$spy_skip',_,R), erase(R), fail ; true ),
 	'$set_yap_flags'(10,1).
-'$action'(33,_,_,_,_) :- !,			% ! g		execute
+'$action'(0'!,_,_,_,_) :- !,			% ! g		execute
 	read(user,G),
 	% don't allow yourself to be caught by creep.
 	'$access_yap_flags'(10, CL),
 	'$set_yap_flags'(10, 0),
 	( '$execute'(G) -> true ; true),
 	'$set_yap_flags'(10, CL),
-	!,
-	'$skipeol'(33),
+%	'$skipeol'(0'!),
 	fail.
 '$action'(0'<,_,_,_,_) :- !,			% <Depth
 	'$new_deb_depth',
diff --git a/pl/utils.yap b/pl/utils.yap
index 6b94ab335..853822368 100644
--- a/pl/utils.yap
+++ b/pl/utils.yap
@@ -477,20 +477,42 @@ garbage_collect_atoms :-
 '$good_character_code'(X) :- integer(X), X > -2, X < 256.
 
 atom_concat(X,Y,At) :-
-	var(X), var(Y), !,
-	atom_length(At,Len),
-	'$atom_contact_split'(At,0,Len,X,Y).
-/* Let atom_chars do our error handling */
-atom_concat(X,Y,At) :-
-	atom_concat([X,Y],At).
+	(
+	  nonvar(X),  nonvar(Y)
+	->
+	  atom_concat([X,Y],At)
+	;
+	  atom(At) ->
+	  atom_length(At,Len),
+	  '$atom_contact_split'(At,0,Len,X,Y)
+	;
+	  var(At) ->
+	  '$do_error'(instantiation_error,atom_concat(X,Y,At))
+	;
+	  '$do_error'(type_error(atom,At),atomic_concant(X,Y,At))
+	).
 
 atomic_concat(X,Y,At) :-
-	var(X), var(Y), !,
-	atom_length(At,Len),
-	'$atom_contact_split'(At,0,Len,X,Y).
-/* Let atom_chars do our error handling */
-atomic_concat(X,Y,At) :-
-	atomic_concat([X,Y],At).
+	(
+	  nonvar(X),  nonvar(Y)
+	->
+	  atomic_concat([X,Y],At)
+	;
+	  atom(At) ->
+	  atom_length(At,Len),
+	  '$atom_contact_split'(At,0,Len,X,Y)
+	;
+	  number(At) ->
+	  number_codes(At,Codes),
+	  '$append'(X0,Y0,Codes),
+	  name(X,X0),
+	  name(Y,Y0)
+	;
+	  var(At) ->
+	  '$do_error'(instantiation_error,atomic_concat(X,Y,At))
+	;
+	  '$do_error'(type_error(atomic,At),atomic_concant(X,Y,At))
+	).
 
 '$atom_contact_split'(At,Len,Len,X,Y) :- !,
 	'$atom_split'(At,Len,X,Y).