diff --git a/C/dbase.c b/C/dbase.c
index 09992e66b..f47065aa7 100644
--- a/C/dbase.c
+++ b/C/dbase.c
@@ -4558,7 +4558,8 @@ mega_instance(yamop *code, PredEntry *ap)
     CELL *ptr;
 
     if (IsVarTerm(t2)) {
-      Yap_unify(ARG2, (t2 = Yap_MkNewApplTerm(f,arity)));
+      t2 = Yap_MkNewApplTerm(f,arity);
+      Yap_unify(ARG2, t2);
     } else if (!IsApplTerm(t2) || FunctorOfTerm(t2) != f) {
       return FALSE;
     }
diff --git a/C/iopreds.c b/C/iopreds.c
index cad12698c..95ab12e05 100644
--- a/C/iopreds.c
+++ b/C/iopreds.c
@@ -4165,26 +4165,26 @@ format(volatile Term otail, volatile Term oargs, int sno)
 	    f_putc = format_putc;
 	    break;
 	  do_instantiation_error:
-	    Yap_Error(INSTANTIATION_ERROR, t, "format/2");
+	    Yap_Error(INSTANTIATION_ERROR, t, "format(\"%s\",_) ", fstr);
 	    goto do_default_error;
 	  do_type_int_error:
-	    Yap_Error(TYPE_ERROR_INTEGER, t, "format/2");
+	    Yap_Error(TYPE_ERROR_INTEGER, t, "format(\"%s\",_) ", fstr);
 	    goto do_default_error;
 	  do_type_number_error:
-	    Yap_Error(TYPE_ERROR_NUMBER, t, "format/2");
+	    Yap_Error(TYPE_ERROR_NUMBER, t, "format(\"%s\",_) ", fstr);
 	    goto do_default_error;
 	  do_type_atom_error:
-	    Yap_Error(TYPE_ERROR_ATOM, t, "format/2");
+	    Yap_Error(TYPE_ERROR_ATOM, t, "format(\"%s\",_) ", fstr);
 	    goto do_default_error;
 	  do_domain_not_less_zero_error:
-	    Yap_Error(DOMAIN_ERROR_NOT_LESS_THAN_ZERO, t, "format/2");
+	    Yap_Error(DOMAIN_ERROR_NOT_LESS_THAN_ZERO, t, "format(\"%s\",_) ", fstr);
 	    goto do_default_error;
 	  do_domain_error_radix:
-	    Yap_Error(DOMAIN_ERROR_RADIX, t, "format/2");
+	    Yap_Error(DOMAIN_ERROR_RADIX, t, "format(\"%s\",_) ", fstr);
 	    goto do_default_error;
 	  do_consistency_error:
 	  default:
-	    Yap_Error(CONSISTENCY_ERROR, oargs, "format/2");
+	    Yap_Error(CONSISTENCY_ERROR, oargs, "format(\"%s\",_) ", fstr);
 	  do_default_error:
 	    if (tnum <= 8)
 	      targs = NULL;
diff --git a/H/clause.h b/H/clause.h
index 4776bb9cf..25fd43e59 100644
--- a/H/clause.h
+++ b/H/clause.h
@@ -290,12 +290,12 @@ Yap_MkMegaRefTerm(PredEntry *ap,yamop *ipc)
 static inline yamop * 
 Yap_MegaClauseFromTerm(Term t)
 {
-  return (yamop *)IntegerOfTerm(ArgOfTerm(1,t));
+  return (yamop *)IntegerOfTerm(ArgOfTerm(2,t));
 }
 
 static inline PredEntry * 
 Yap_MegaClausePredicateFromTerm(Term t)
 {
-  return (PredEntry *)IntegerOfTerm(ArgOfTerm(2,t));
+  return (PredEntry *)IntegerOfTerm(ArgOfTerm(1,t));
 }