diff --git a/src/tgba/tgbamask.cc b/src/tgba/tgbamask.cc
index 1cbdf066e..9fea6a279 100644
--- a/src/tgba/tgbamask.cc
+++ b/src/tgba/tgbamask.cc
@@ -76,49 +76,8 @@ namespace spot
       transitions::const_iterator it_;
     };
 
-
-    class tgba_mask_keep: public tgba_mask
-    {
-      const state_set& mask_;
-    public:
-      tgba_mask_keep(const tgba* masked,
-		     const state_set& mask,
-		     const state* init)
-	: tgba_mask(masked, init),
-	  mask_(mask)
-      {
-      }
-
-      bool wanted(const state* s) const
-      {
-	state_set::const_iterator i = mask_.find(s);
-	return i != mask_.end();
-      }
-    };
-
-    class tgba_mask_ignore: public tgba_mask
-    {
-      const state_set& mask_;
-    public:
-      tgba_mask_ignore(const tgba* masked,
-		       const state_set& mask,
-		       const state* init)
-	: tgba_mask(masked, init),
-	  mask_(mask)
-      {
-      }
-
-      bool wanted(const state* s) const
-      {
-	state_set::const_iterator i = mask_.find(s);
-	return i == mask_.end();
-      }
-    };
-
-
   }
 
-
   tgba_mask::tgba_mask(const tgba* masked,
 		       const state* init)
     : tgba_proxy(masked),
@@ -155,19 +114,79 @@ namespace spot
     for (auto it: original_->succ(state))
       {
 	const spot::state* s = it->current_state();
-	if (!wanted(s))
+	bdd acc = it->current_acceptance_conditions();
+	if (!wanted(s, acc))
 	  {
 	    s->destroy();
 	    continue;
 	  }
-	transition t = { s,
-			 it->current_condition(),
-			 it->current_acceptance_conditions() };
-	res->trans_.push_back(t);
+	res->trans_.emplace_back(transition {s, it->current_condition(), acc});
       }
     return res;
   }
 
+  namespace
+  {
+
+    class tgba_mask_keep: public tgba_mask
+    {
+      const state_set& mask_;
+    public:
+      tgba_mask_keep(const tgba* masked,
+		     const state_set& mask,
+		     const state* init)
+	: tgba_mask(masked, init),
+	  mask_(mask)
+      {
+      }
+
+      bool wanted(const state* s, const bdd&) const
+      {
+	state_set::const_iterator i = mask_.find(s);
+	return i != mask_.end();
+      }
+    };
+
+    class tgba_mask_ignore: public tgba_mask
+    {
+      const state_set& mask_;
+    public:
+      tgba_mask_ignore(const tgba* masked,
+		       const state_set& mask,
+		       const state* init)
+	: tgba_mask(masked, init),
+	  mask_(mask)
+      {
+      }
+
+      bool wanted(const state* s, const bdd&) const
+      {
+	state_set::const_iterator i = mask_.find(s);
+	return i == mask_.end();
+      }
+    };
+
+    class tgba_mask_acc_ignore: public tgba_mask
+    {
+      const bdd& mask_;
+    public:
+      tgba_mask_acc_ignore(const tgba* masked,
+			   const bdd& mask,
+			   const state* init)
+	: tgba_mask(masked, init),
+	  mask_(mask)
+      {
+      }
+
+      bool wanted(const state*, const bdd& acc) const
+      {
+	return (acc & mask_) == bddfalse;
+      }
+    };
+
+
+  }
+
 
   const tgba*
   build_tgba_mask_keep(const tgba* to_mask,
@@ -185,4 +204,12 @@ namespace spot
     return new tgba_mask_ignore(to_mask, to_ignore, init);
   }
 
+  const tgba*
+  build_tgba_mask_acc_ignore(const tgba* to_mask,
+			     const bdd to_ignore,
+			     const state* init)
+  {
+    return new tgba_mask_acc_ignore(to_mask, to_ignore, init);
+  }
+
 }
diff --git a/src/tgba/tgbamask.hh b/src/tgba/tgbamask.hh
index 7c29299da..cd38789da 100644
--- a/src/tgba/tgbamask.hh
+++ b/src/tgba/tgbamask.hh
@@ -21,6 +21,7 @@
 # define SPOT_TGBA_TGBAMASK_HH
 
 #include "tgbaproxy.hh"
+#include "bdd.h"
 
 namespace spot
 {
@@ -50,7 +51,7 @@ namespace spot
     virtual tgba_succ_iterator*
     succ_iter(const state* local_state) const;
 
-    virtual bool wanted(const state* s) const = 0;
+    virtual bool wanted(const state* s, const bdd& acc) const = 0;
 
   protected:
     const state* init_;
@@ -78,6 +79,23 @@ namespace spot
 			 const state_set& to_ignore,
 			 const state* init = 0);
 
+
+  /// \ingroup tgba_on_the_fly_algorithms
+  /// \brief Mask a TGBA, rejecting some acceptance set of transitions.
+  ///
+  /// This will ignore all transitions labeled by the acceptance ACC
+  /// such that ACC & TO_IGNORE != bddfalse.  The initial state can
+  /// optionally be reset to \a init.
+  ///
+  /// Note that the acceptance condition of the automaton (i.e. the
+  /// set of all acceptance set) is not changed, because so far this
+  /// function is only needed in graph algorithms that do not call
+  /// all_acceptance_conditions().
+  SPOT_API const tgba*
+  build_tgba_mask_acc_ignore(const tgba* to_mask,
+			     const bdd to_ignore,
+			     const state* init = 0);
+
 }
 
 #endif // SPOT_TGBA_TGBAMASK_HH
diff --git a/src/tgbatest/.gitignore b/src/tgbatest/.gitignore
index 1b45a65fe..36469b686 100644
--- a/src/tgbatest/.gitignore
+++ b/src/tgbatest/.gitignore
@@ -19,6 +19,7 @@ ltlmagic
 ltlprod
 Makefile
 Makefile.in
+maskacc
 mixprod
 output1
 output2
diff --git a/src/tgbatest/Makefile.am b/src/tgbatest/Makefile.am
index ab8edbd56..025752996 100644
--- a/src/tgbatest/Makefile.am
+++ b/src/tgbatest/Makefile.am
@@ -42,6 +42,7 @@ check_PROGRAMS = \
   intvcomp \
   intvcmp2 \
   ltlprod \
+  maskacc \
   mixprod \
   powerset \
   readsat \
@@ -64,6 +65,7 @@ intvcomp_SOURCES = intvcomp.cc
 intvcmp2_SOURCES = intvcmp2.cc
 ltl2tgba_SOURCES = ltl2tgba.cc
 ltlprod_SOURCES  = ltlprod.cc
+maskacc_SOURCES  = maskacc.cc
 mixprod_SOURCES  = mixprod.cc
 powerset_SOURCES = powerset.cc
 randtgba_SOURCES = randtgba.cc
@@ -89,6 +91,7 @@ TESTS = \
   neverclaimread.test \
   dstar.test \
   readsave.test \
+  maskacc.test \
   simdet.test \
   sim.test \
   sim2.test \
diff --git a/src/tgbatest/maskacc.cc b/src/tgbatest/maskacc.cc
new file mode 100755
index 000000000..1d392b686
--- /dev/null
+++ b/src/tgbatest/maskacc.cc
@@ -0,0 +1,69 @@
+// Copyright (C) 2014 Laboratoire de Recherche et DĂ©veloppement
+// de l'Epita (LRDE).
+//
+// This file is part of Spot, a model checking library.
+//
+// Spot is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+//
+// Spot is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+// or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+// License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include <iostream>
+#include <cassert>
+#include <cstdlib>
+#include "tgbaparse/public.hh"
+#include "tgbaalgos/save.hh"
+#include "tgba/tgbamask.hh"
+#include "ltlast/allnodes.hh"
+
+void
+syntax(char* prog)
+{
+  std::cerr << prog << " file" << std::endl;
+  exit(2);
+}
+
+int
+main(int argc, char** argv)
+{
+  int exit_code = 0;
+
+  if (argc != 2)
+    syntax(argv[0]);
+
+  spot::bdd_dict* dict = new spot::bdd_dict();
+
+  spot::ltl::environment& env(spot::ltl::default_environment::instance());
+  spot::tgba_parse_error_list pel;
+  spot::tgba_explicit_string* aut = spot::tgba_parse(argv[1], pel, dict, env);
+  if (spot::format_tgba_parse_errors(std::cerr, argv[1], pel))
+    return 2;
+
+  bdd all = aut->all_acceptance_conditions();
+  while (all != bddfalse)
+    {
+      bdd one = bdd_satone(all);
+      all -= one;
+
+      const spot::tgba* masked = spot::build_tgba_mask_acc_ignore(aut, one);
+      spot::tgba_save_reachable(std::cout, masked);
+      delete masked;
+    }
+
+  assert(spot::ltl::unop::instance_count() == 0);
+  assert(spot::ltl::binop::instance_count() == 0);
+  assert(spot::ltl::multop::instance_count() == 0);
+  assert(spot::ltl::atomic_prop::instance_count() != 0);
+  delete aut;
+  assert(spot::ltl::atomic_prop::instance_count() == 0);
+  delete dict;
+  return exit_code;
+}
diff --git a/src/tgbatest/maskacc.test b/src/tgbatest/maskacc.test
new file mode 100755
index 000000000..0e6bb711e
--- /dev/null
+++ b/src/tgbatest/maskacc.test
@@ -0,0 +1,50 @@
+#!/bin/sh
+# Copyright (C) 2014 Laboratoire de Recherche et Développement de
+# l'Epita (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+. ./defs
+
+set -e
+
+cat >input1 <<EOF
+acc = A B;
+s1, s2, "a", A;
+s1, s3, "b", B;
+s2, s3, "a",;
+s3, s2, "b",;
+s2, s4, "a", B;
+s3, s4, "b", A;
+s4, s4, "a", A B;
+EOF
+
+cat >expect1 <<EOF
+acc = "B" "A";
+"s1", "s2", "a", "A";
+"s2", "s3", "a",;
+"s3", "s2", "b",;
+"s3", "s4", "b", "A";
+acc = "B" "A";
+"s1", "s3", "b", "B";
+"s3", "s2", "b",;
+"s2", "s3", "a",;
+"s2", "s4", "a", "B";
+EOF
+
+run 0 ../maskacc input1 | tee stdout
+diff stdout expect1