diff --git a/src/ltlast/unop.cc b/src/ltlast/unop.cc
index e65a43b28..ab9b9c686 100644
--- a/src/ltlast/unop.cc
+++ b/src/ltlast/unop.cc
@@ -68,8 +68,10 @@ namespace spot
 	  is.psl_formula = false;
 	  is.accepting_eword = false;
 	  break;
-	case Closure:
 	case NegClosure:
+	  is.not_marked = false;
+	  // fall through
+	case Closure:
 	  is.boolean = false;
 	  is.ltl_formula = false;
 	  is.eltl_formula = false;
diff --git a/src/ltlvisit/mark.cc b/src/ltlvisit/mark.cc
index 8ab52cad9..61c3a8dd3 100644
--- a/src/ltlvisit/mark.cc
+++ b/src/ltlvisit/mark.cc
@@ -29,103 +29,6 @@ namespace spot
   {
     namespace
     {
-
-      class has_mark_visitor : public visitor
-      {
-	bool result_;
-      public:
-	has_mark_visitor()
-	  : result_(false)
-	{
-	}
-	~has_mark_visitor()
-	{
-	}
-
-	bool
-	result()
-	{
-	  return result_;
-	}
-
-	void
-	visit(atomic_prop*)
-	{
-	}
-
-	void
-	visit(constant*)
-	{
-	}
-
-	void
-	visit(bunop*)
-	{
-	}
-
-	void
-	visit(unop* uo)
-	{
-	  switch (uo->op())
-	    {
-	    case unop::NegClosure:
-	      result_ = true;
-	      return;
-	    case unop::Finish:
-	    case unop::Closure:
-	    case unop::Not:
-	    case unop::X:
-	    case unop::F:
-	    case unop::G:
-	      return;
-	    }
-	  /* Unreachable code. */
-	  assert(0);
-	}
-
-	void
-	visit(automatop*)
-	{
-	}
-
-	void
-	visit(multop* mo)
-	{
-	  unsigned mos = mo->size();
-	  for (unsigned i = 0; i < mos && !result_; ++i)
-	    result_ = recurse(mo->nth(i));
-	}
-
-	void
-	visit(binop* bo)
-	{
-	  switch (bo->op())
-	    {
-	    case binop::EConcatMarked:
-	      result_ = true;
-	      return;
-	    case binop::Xor:
-	    case binop::Implies:
-	    case binop::Equiv:
-	    case binop::U:
-	    case binop::W:
-	    case binop::M:
-	    case binop::R:
-	    case binop::EConcat:
-	    case binop::UConcat:
-	      return;
-	    }
-	  /* Unreachable code. */
-	  assert(0);
-	}
-
-	bool
-	recurse(const formula* f)
-	{
-	  return has_mark(f);
-	}
-      };
-
       class simplify_mark_visitor : public visitor
       {
 	formula* result_;
@@ -415,15 +318,5 @@ namespace spot
       return v.has_mark();
     }
 
-    bool
-    has_mark(const formula* f)
-    {
-      has_mark_visitor v;
-      const_cast<formula*>(f)->accept(v);
-      return v.result();
-    }
-
-
-
   }
 }
diff --git a/src/ltlvisit/mark.hh b/src/ltlvisit/mark.hh
index eee6cca5a..834e14da6 100644
--- a/src/ltlvisit/mark.hh
+++ b/src/ltlvisit/mark.hh
@@ -35,8 +35,6 @@ namespace spot
     formula* mark_concat_ops(const formula* f);
 
     bool simplify_mark(formula*& f);
-
-    bool has_mark(const formula* f);
   }
 }
 
diff --git a/src/tgbaalgos/ltl2tgba_fm.cc b/src/tgbaalgos/ltl2tgba_fm.cc
index 85c3107c7..b3ee310f6 100644
--- a/src/tgbaalgos/ltl2tgba_fm.cc
+++ b/src/tgbaalgos/ltl2tgba_fm.cc
@@ -1394,7 +1394,7 @@ namespace spot
 	  *new_flag = true;
 
 	// Perform the actual translation.
-	v_.reset(!has_mark(f));
+	v_.reset(!f->is_marked());
 	f->accept(v_);
 	translated t;
 	t.symbolic = v_.result();