diff --git a/C/c_interface.c b/C/c_interface.c
index 945ca8440..1d4db22d4 100644
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -1584,6 +1584,7 @@ run_emulator(YAP_dogoalinfo *dgi)
 {
   choiceptr myB;
   int out;
+  BACKUP_MACHINE_REGS();
 
   Yap_PrologMode = UserMode;
   out = Yap_absmi(0);
@@ -1656,6 +1657,7 @@ X_API int
 YAP_RetryGoal(YAP_dogoalinfo *dgi)
 {
   choiceptr myB;
+  int out;
 
   BACKUP_MACHINE_REGS();
   myB = (choiceptr)(LCL0-dgi->b);
@@ -1665,7 +1667,9 @@ YAP_RetryGoal(YAP_dogoalinfo *dgi)
     return FALSE;
   }
   P = FAILCODE;
-  return run_emulator(dgi);
+  out = run_emulator(dgi);
+  RECOVER_MACHINE_REGS();
+  return out;
 }
 
 X_API int
@@ -1673,6 +1677,7 @@ YAP_LeaveGoal(int backtrack, YAP_dogoalinfo *dgi)
 {
   choiceptr myB;
 
+  BACKUP_MACHINE_REGS();
   myB = (choiceptr)(LCL0-dgi->b);
   if (B > myB) {
     /* someone cut us */
@@ -2588,6 +2593,7 @@ YAP_ExtendList(Term t0, Term inp)
 {
   Term t;
   CELL *ptr = RepPair(t0);
+  BACKUP_H();
 
   ptr[0] = inp;
   ptr[1] = AbsPair(ptr+2);
diff --git a/C/exec.c b/C/exec.c
index 219b15ed8..d1835c410 100644
--- a/C/exec.c
+++ b/C/exec.c
@@ -1506,6 +1506,10 @@ clean_trail(Term t, DBTerm *dbt, Term t0)
 {
   tr_fr_ptr pt1, pbase;
 
+#ifdef SHADOW_HB
+  register CELL *HBREG = HB;
+#endif /* SHADOW_HB */
+
   pbase = B->cp_tr;
   pt1 = TR - 1;
   while (pt1 >= pbase) {