diff --git a/C/absmi.c b/C/absmi.c
index 9cda0fc86..fd9fdf9b7 100644
--- a/C/absmi.c
+++ b/C/absmi.c
@@ -2159,8 +2159,17 @@ Yap_absmi(int inp)
       /* also, this is unusual in that I have already done deallocate,
 	 so I don't need to redo it.
        */ 
-    NoStackDeallocate:
+    NoStackProceed:
       if (CFREG == (CELL)(LCL0+2)) {
+	/*
+	  we're not actually doing debugging here, just execute
+	  instruction and go on.
+	*/
+	PREG = CPREG;
+	YREG = ENV;
+#ifdef DEPTH_LIMIT
+	DEPTH = YREG[E_DEPTH];
+#endif
 	JMPNext();
       }
       ASP = YREG;
@@ -2557,12 +2566,19 @@ Yap_absmi(int inp)
       JMPNext();
 
       BOp(procceed, e);
-      PREG = CPREG;
-      YREG = ENV;
-#ifdef DEPTH_LIMIT
-      DEPTH = YREG[E_DEPTH];
+      CACHE_Y_AS_ENV(YREG);
+#ifndef NO_CHECKING
+      /* check stacks */
+      check_stack(NoStackProceed, H);
 #endif
+      PREG = CPREG;
+      E_YREG = ENV;
+#ifdef DEPTH_LIMIT
+      DEPTH = E_YREG[E_DEPTH];
+#endif
+      WRITEBACK_Y_AS_ENV();
       JMPNext();
+      ENDCACHE_Y_AS_ENV();
       ENDBOp();
 
       Op(allocate, e);
@@ -2605,13 +2621,6 @@ Yap_absmi(int inp)
       else
 	E_YREG = (CELL *) ((CELL) E_YREG + ENV_Size(CPREG));
 #endif /* FROZEN_STACKS */
-#ifndef NO_CHECKING
-      if (Yap_do_low_level_trace) {
-	fprintf(stderr, "H is %p, YENV is %p\n", H, YENV);
-      }
-      /* check stacks */
-      check_stack(NoStackDeallocate, H);
-#endif
       WRITEBACK_Y_AS_ENV();
       ENDCACHE_Y_AS_ENV();
       GONext();
diff --git a/C/computils.c b/C/computils.c
index e6bdff242..ef2c7a16c 100644
--- a/C/computils.c
+++ b/C/computils.c
@@ -553,7 +553,6 @@ static char *opformat[] =
   "jump\t\t%l",
   "jump\t\t%l",
   "proceed",
-  "safe_proceed",
   "call\t\t%p,%d,%z",
   "execute\t\t%p",
   "sys\t\t%p",
diff --git a/C/heapgc.c b/C/heapgc.c
index 2394ca07f..8cca4c922 100644
--- a/C/heapgc.c
+++ b/C/heapgc.c
@@ -43,6 +43,10 @@ static Int      tot_gc_recovered = 0; /* number of heap objects in all garbage c
 /* in a single gc */
 static unsigned long int   total_marked;	/* number of heap objects marked */
 
+#ifdef COROUTINING
+static unsigned long int   total_smarked;
+#endif
+
 struct gc_ma_h_entry *live_list;
 
 STATIC_PROTO(Int  p_inform_gc, (void));
@@ -876,15 +880,18 @@ mark_variable(CELL_PTR current)
 	  current = next;
 	}
       goto begin;
-    }
 #ifdef DEBUG
-    else if (next < (CELL *)AtomBase || next < (CELL *)HeapTop)
+    } else if (next < (CELL *)AtomBase || next < (CELL *)HeapTop) {
       fprintf(Yap_stderr, "ooops while marking %lx, %p at %p\n", (unsigned long int)ccur, current, next);
 #endif
+    } else {
+#ifdef COROUTING
+      total_smarked++;
+#endif      
 #ifdef INSTRUMENT_GC
-    else
       inc_var(current, next);
 #endif
+    }
     POP_CONTINUATION();
   } else if (IsPairTerm(ccur)) {
 #ifdef INSTRUMENT_GC
@@ -2954,7 +2961,11 @@ compaction_phase(tr_fr_ptr old_TR, CELL *current_env, yamop *curp, CELL *max)
   sweep_trail(B, old_TR);
 #ifdef HYBRID_SCHEME
 #ifdef DEBUG
-  if (total_marked != iptop-(CELL_PTR *)H && iptop < (CELL_PTR *)ASP -1024)
+  if (total_marked
+#ifdef COROUTINING
+      -total_smarked
+#endif
+      != iptop-(CELL_PTR *)H && iptop < (CELL_PTR *)ASP -1024)
     fprintf(Yap_stderr,"[GC] Oops on iptop-H (%ld) vs %ld\n", (unsigned long int)(iptop-(CELL_PTR *)H), total_marked);
 #endif
   if (iptop < (CELL_PTR *)ASP && 10*total_marked < H-H0) {
@@ -3059,6 +3070,9 @@ do_gc(Int predarity, CELL *current_env, yamop *nextop)
   }
   time_start = Yap_cputime();
   total_marked = 0;
+#ifdef COROUTING
+  total_smarked = 0;
+#endif
   discard_trail_entries = 0;
 #ifdef HYBRID_SCHEME
   iptop = (CELL_PTR *)H;
diff --git a/C/index.c b/C/index.c
index 9b641890a..224174d64 100644
--- a/C/index.c
+++ b/C/index.c
@@ -5427,6 +5427,10 @@ Yap_AddClauseToIndex(PredEntry *ap, yamop *beg, int first) {
   path_stack_entry *stack, *sp;
   int cb;
 
+  if (!(ap->PredFlags & LogUpdatePredFlag)) {
+    Yap_RemoveIndexation(ap);
+    return;
+  }
   if ((cb = setjmp(Yap_CompilerBotch)) == 3) {
     restore_machine_regs();
     Yap_gcl(Yap_Error_Size, ap->ArityOfPE, ENV, CP);