diff --git a/C/tracer.c b/C/tracer.c
index f2a70a169..0c2c9c9bf 100644
--- a/C/tracer.c
+++ b/C/tracer.c
@@ -161,13 +161,6 @@ low_level_trace(yap_low_level_port port, PredEntry *pred, CELL *args)
   LOCK(Yap_heap_regs->low_level_trace_lock);
   sc = Yap_heap_regs;
   vsc_count++;
-  if (B->cp_tr < B->cp_b->cp_tr || TR < B->cp_tr)
-    fprintf(stderr,"Here we go %lld\n", vsc_count);
-  if (vsc_count < 13600)
-    {
-      UNLOCK(Yap_heap_regs->low_level_trace_lock);
-      return;
-    }
 #ifdef COMMENTED
   if (worker_id != 04 || worker_id != 03) return;
   //  if (vsc_count == 218280)
diff --git a/changes-5.1.html b/changes-5.1.html
index 8d531e6fd..ceaac5273 100644
--- a/changes-5.1.html
+++ b/changes-5.1.html
@@ -16,7 +16,9 @@
 
 <h2>Yap-5.1.2:</h2>
 <ul>
-<li> FIXED:  make 128 maximum disjunction depth.</li> 
+<li> FIXED:  avl_new/1 (obs from Miguel Filgueiras).</li> 
+<li> FIXED:  broken all/3 (obs from Miguel Filgueiras).</li> 
+<li> FIXED:  make 128 maximum disjunction depth (obs from Nicos Angelopoulos).</li> 
 <li> FIXED:  first cut at using timestamps with logical updates.</li> 
 <li> FIXED:  indexing on doubles wasn't working properly.</li> 
 <li> FIXED:  sending large lists of atomics to DB was very, very slow.</li> 
diff --git a/docs/yap.tex b/docs/yap.tex
index 0011a2586..a7ec111d6 100644
--- a/docs/yap.tex
+++ b/docs/yap.tex
@@ -7115,7 +7115,13 @@ insert and lookup elements in the tree. Please try red-black trees if
 you need deletion.
 
 @table @code
-@item avl_insert(+@var{Key},?@var{Value},+@var{T0},+@var{TF})
+@item avl_new(+@var{T})
+@findex avl_new/1
+@snindex avl_new/1
+@cnindex avl_new/1
+Create a new tree.
+
+@item avl_insert(+@var{Key},?@var{Value},+@var{T0},-@var{TF})
 @findex avl_insert/4
 @snindex avl_insert/4
 @cnindex avl_insert/4
diff --git a/library/avl.yap b/library/avl.yap
index a0ec8e2c6..17288656b 100644
--- a/library/avl.yap
+++ b/library/avl.yap
@@ -16,10 +16,13 @@
 *************************************************************************/
 
 :- module(avl, [
+	avl_new/1,
 	avl_insert/4,
 	avl_lookup/3
           ]).
 
+avl_new([]).
+
 avl_insert(Key, Value, T0, TF) :-
 	insert(T0, Key, Value, TF, _).
 
diff --git a/pl/setof.yap b/pl/setof.yap
index 4d9ac2844..a876c3dfd 100644
--- a/pl/setof.yap
+++ b/pl/setof.yap
@@ -189,6 +189,7 @@ all(T,G,S) :-
 % $$set does its best to preserve space
 '$$set'(S,R) :- 
        '$$build'(S0,_,R),
+        S0 = [_|_],
 	S = S0.
 
 '$$build'(Ns,S0,R) :- '$db_dequeue'(R,X), !,