diff --git a/C/heapgc.c b/C/heapgc.c
index badd63c7e..1c8aaf386 100644
--- a/C/heapgc.c
+++ b/C/heapgc.c
@@ -2090,12 +2090,12 @@ mark_choicepoints(register choiceptr gc_B, tr_fr_ptr saved_TR, bool very_verbose
     restart_cp:
       switch (opnum) {
       case _Nstop:
-	if (gc_B->cp_b != NULL) {
-	  nargs = 0;
-	  break;
-	} else {
-	  /* this is the last choice point, the work is done  ;-) */
-	  return;
+	if (gc_B->cp_env == LCL0) {
+        return;
+    } else {
+	    // This must be a border choicepoint, just move up
+	    gc_B = (choiceptr)(gc_B->cp_env[E_B]);
+	    continue;
 	}
       case _retry_c:
       case _retry_userc:
@@ -3025,11 +3025,14 @@ sweep_choicepoints(choiceptr gc_B USES_REGS)
       sweep_environments(gc_B->cp_env,
 			 EnvSizeInCells,
 			 NULL PASS_REGS);
-      if (gc_B->cp_b != NULL) {
-	break;
-      } else
-	return;
-    case _trust_fail:
+            if (gc_B->cp_env == LCL0) {
+                return;
+            } else {
+                // This must be a border choicepoint, just move up
+                gc_B = (choiceptr)(gc_B->cp_env[E_B]);
+                continue;
+            }
+        case _trust_fail:
       break;
     case _or_else:
     case _or_last:
diff --git a/C/utilpreds.c b/C/utilpreds.c
index 2247f9344..153f8abbb 100644
--- a/C/utilpreds.c
+++ b/C/utilpreds.c
@@ -52,14 +52,13 @@ typedef struct non_single_struct_t {
   }
 
 #define def_aux_overflow()						\
-  aux_overflow:{							\
+  while (to_visit_max-to_visit0 < 32) {							\
     size_t d1 = to_visit-to_visit0;					\
-    size_t d2 = to_visit_max-to_visit0;					\
-    to_visit0 = Realloc(to_visit0,(d2+128)*sizeof(struct non_single_struct_t)); \
+    size_t d2 = to_visit_max-to_visit0;             \
+    size_t d3 = Yap_Min(d2+1024, d2 *2);					\
+    to_visit0 = Realloc(to_visit0,d3*sizeof(struct non_single_struct_t)); \
     to_visit = to_visit0+d1;						\
-    to_visit_max = to_visit0+(d2+128);					\
-    pt0--;								\
-    goto restart;							\
+    to_visit_max = to_visit0+(d3);					\
   }
 
 #define def_global_overflow()			\