diff --git a/C/index.c b/C/index.c
index e373e1a04..68dd1d4fe 100644
--- a/C/index.c
+++ b/C/index.c
@@ -11,8 +11,12 @@
 * File:		index.c							 *
 * comments:	Indexing a Prolog predicate				 *
 *									 *
-* Last rev:     $Date: 2008-01-24 00:11:59 $,$Author: vsc $						 *
+* Last rev:     $Date: 2008-01-24 10:20:42 $,$Author: vsc $						 *
 * $Log: not supported by cvs2svn $
+* Revision 1.194  2008/01/24 00:11:59  vsc
+* garbage collector was not asking for space.
+* avoid 0 sized calls to mmap.
+*
 * Revision 1.193  2008/01/23 17:57:46  vsc
 * valgrind it!
 * enable atom garbage collection.
@@ -8422,6 +8426,8 @@ Yap_FollowIndexingCode(PredEntry *ap, yamop *ipc, Term Terms[3], yamop *ap_pc, y
 #endif /* YAPOR */
 	/* I did a trust */
       }
+      if (op == _op_fail)
+	return NULL;
       if (lu_pred)
 	return lu_clause(ipc);
       else
diff --git a/C/tracer.c b/C/tracer.c
index 169310efa..9c47f3c40 100644
--- a/C/tracer.c
+++ b/C/tracer.c
@@ -161,9 +161,16 @@ 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 (FALSE && vsc_count < 59800LL) {
+    UNLOCK(Yap_heap_regs->low_level_trace_lock);
+    return;
+  }
+  if (FALSE && vsc_count == 59855LL) {
+    jmp_deb(1);
+  }
+#ifdef COMMENTED
   //*(H0+(0xb65f2850-0xb64b2008)/sizeof(CELL))==0xc || 
   //0x4fd4d
-#ifdef COMMENTED
   if (vsc_count == 40650191LL)
     jmp_deb(1);
   return;
diff --git a/changes-5.1.html b/changes-5.1.html
index 1351cf901..66258cc00 100644
--- a/changes-5.1.html
+++ b/changes-5.1.html
@@ -17,6 +17,7 @@
 
 <h2>Yap-5.1.3:</h2>
 <ul>
+<li> FIXED: clause/3 should not follow fail.</li>
 <li> FIXED: make sure we don't ask for 0-sized blocks, minimal 64K.</li>
 <li> FIXED: Aux reallocation should always increase aux size.</li>
 <li> NEW: start atom garbage collector by default (except for threads).</li>