diff --git a/C/tracer.c b/C/tracer.c
index 54e333105..720839e11 100644
--- a/C/tracer.c
+++ b/C/tracer.c
@@ -113,7 +113,7 @@ check_trail_consistency(void) {
       } else {
 	if (IsPairTerm(TrailTerm(ptr))) {
 	  CELL *p = RepPair(TrailTerm(ptr));
-	  if (p < H0) continue;
+	  if IsAttVar(p) continue;
 	}
 	printf("Oops at call %ld, B->cp(%p) TR(%p)  pt(%p)\n", vsc_count,B->cp_tr, TR, ptr);
 	return(FALSE);
diff --git a/H/amiops.h b/H/amiops.h
index a4111c514..b2968f037 100644
--- a/H/amiops.h
+++ b/H/amiops.h
@@ -354,7 +354,7 @@ Binding Macros for Multiple Assignment Variables.
 
 #define BIND_GLOBALCELL(A,D)    *(A) = (D); \
 				if ((A) >= HBREG) continue; \
-                                TRAIL_GLOBAL(A,D); if ((A) >= H0) continue; \
+                                TRAIL_GLOBAL(A,D); if (!IsAttVar(A)) continue; \
                                 Yap_WakeUp((A)); continue
 
 #define BIND_GLOBALCELL_NONATT(A,D)    *(A) = (D); \
@@ -502,7 +502,7 @@ Yap_unify_constant(register Term a, register Term cons)
   BIND(pt,cons,wake_for_cons);
 #ifdef COROUTINING
   DO_TRAIL(pt, cons);
-  if (pt < H0) Yap_WakeUp(pt);
+  if (IsAttVar(pt)) Yap_WakeUp(pt);
  wake_for_cons:
 #endif
   return(TRUE);