diff --git a/src/tgba/tgba.cc b/src/tgba/tgba.cc
index 91b286c4c..9089ee038 100644
--- a/src/tgba/tgba.cc
+++ b/src/tgba/tgba.cc
@@ -41,10 +41,7 @@ namespace spot
     if (last_support_conditions_input_)
       last_support_conditions_input_->destroy();
     delete iter_cache_;
-
-    // Destroy all named properties.
-    for (auto& np: named_prop_)
-      np.second.second(np.second.first);
+    release_named_properties();
   }
 
   bdd
diff --git a/src/tgba/tgba.hh b/src/tgba/tgba.hh
index ae7359b99..14c616375 100644
--- a/src/tgba/tgba.hh
+++ b/src/tgba/tgba.hh
@@ -744,6 +744,14 @@ namespace spot
     }
 #endif
 
+    void release_named_properties()
+    {
+      // Destroy all named properties.
+      for (auto& np: named_prop_)
+	np.second.second(np.second.first);
+      named_prop_.clear();
+    }
+
     bool has_state_based_acc() const
     {
       return is.state_based_acc;
diff --git a/src/tgbaalgos/complete.cc b/src/tgbaalgos/complete.cc
index c5d56cfbe..ecd44dbb8 100644
--- a/src/tgbaalgos/complete.cc
+++ b/src/tgbaalgos/complete.cc
@@ -61,6 +61,8 @@ namespace spot
 	  }
       }
 
+    unsigned t = aut->num_transitions();
+
     // Now complete all states (including the sink).
     for (unsigned i = 0; i < n; ++i)
       {
@@ -99,6 +101,13 @@ namespace spot
 	    aut->new_transition(i, sink, missingcond, acc);
 	  }
       }
+
+    // Get rid of any named property if the automaton changed.
+    if (t < aut->num_transitions())
+      aut->release_named_properties();
+    else
+      assert(t == aut->num_transitions());
+
     return sink;
   }
 
diff --git a/src/tgbaalgos/stripacc.cc b/src/tgbaalgos/stripacc.cc
index 841e3d275..81a1c9a4b 100644
--- a/src/tgbaalgos/stripacc.cc
+++ b/src/tgbaalgos/stripacc.cc
@@ -1,6 +1,6 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2012, 2014 Laboratoire de Recherche et Développement
-// de l'Epita (LRDE).
+// Copyright (C) 2012, 2014, 2015 Laboratoire de Recherche et
+// Développement de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
 //
@@ -29,5 +29,6 @@ namespace spot
       for (auto& t: a->out(s))
 	t.acc = 0U;
     a->set_generalized_buchi(0);
+    a->release_named_properties();
   }
 }