diff --git a/C/cdmgr.c b/C/cdmgr.c
index 9dd938664..34374c7f3 100644
--- a/C/cdmgr.c
+++ b/C/cdmgr.c
@@ -2841,7 +2841,7 @@ p_rmspy( USES_REGS1 )
     return FALSE;
   }
 #if THREADS
-  if (!(pred->PredFlags & ThreadLocalPredFlag)) {
+  if (pred->PredFlags & ThreadLocalPredFlag) {
     pred->OpcodeOfPred = Yap_opcode(_thread_local);
     pred->PredFlags ^= SpiedPredFlag;
     UNLOCKPE(39,pred);
@@ -5288,8 +5288,6 @@ p_continue_static_clause( USES_REGS1 )
 static void
 add_code_in_lu_index(LogUpdIndex *cl, PredEntry *pp)
 {
-  CACHE_REGS
-
   char *code_end = (char *)cl + cl->ClSize;
   Yap_inform_profiler_of_clause(cl, code_end, pp, GPROF_LU_INDEX);
   cl = cl->ChildIndex;
@@ -5302,7 +5300,6 @@ add_code_in_lu_index(LogUpdIndex *cl, PredEntry *pp)
 static void
 add_code_in_static_index(StaticIndex *cl, PredEntry *pp)
 {
-  CACHE_REGS
   char *code_end = (char *)cl + cl->ClSize;
   Yap_inform_profiler_of_clause(cl, code_end, pp, GPROF_STATIC_INDEX);
   cl = cl->ChildIndex;
@@ -5315,7 +5312,6 @@ add_code_in_static_index(StaticIndex *cl, PredEntry *pp)
 
 static void
 add_code_in_pred(PredEntry *pp) {
-  CACHE_REGS
   yamop *clcode;
 
   PELOCK(49,pp);
@@ -5387,7 +5383,6 @@ add_code_in_pred(PredEntry *pp) {
 
 void
 Yap_dump_code_area_for_profiler(void) {
-  CACHE_REGS
   ModEntry *me = CurrentModules;
 
   while (me) {
diff --git a/C/compiler.c b/C/compiler.c
index 579d0a167..610ae0e0e 100644
--- a/C/compiler.c
+++ b/C/compiler.c
@@ -916,6 +916,22 @@ c_test(Int Op, Term t1, compiler_struct *cglobs) {
   CACHE_REGS
   Term t = Deref(t1);
 
+  /* be caareful, has to be first occurrence */
+  if (Op == _save_by) {
+    if (!IsNewVar(t)) {
+	char s[32];
+
+	LOCAL_Error_TYPE = TYPE_ERROR_VARIABLE;
+	LOCAL_Error_Term = t;
+	LOCAL_ErrorMessage = LOCAL_ErrorSay;
+	Yap_bip_name(Op, s);
+	sprintf(LOCAL_ErrorMessage, "compiling %s/2 on bound variable", s);
+	save_machine_regs();
+	siglongjmp(cglobs->cint.CompilerBotch,1);
+    }
+    c_var(t, save_b_flag, 1, 0, cglobs);
+    return;
+  }
   if (!IsVarTerm(t) || IsNewVar(t)) {
     Term tn = MkVarTerm();
     c_eq(t, tn, cglobs);
@@ -923,8 +939,6 @@ c_test(Int Op, Term t1, compiler_struct *cglobs) {
   }
   if (Op == _cut_by)
     c_var(t, commit_b_flag, 1, 0, cglobs);
-  else if (Op == _save_by)
-    c_var(t, save_b_flag, 1, 0, cglobs);
   else
     c_var(t, f_flag,(unsigned int)Op, 0, cglobs);
 }