diff --git a/src/misc/Makefile.am b/src/misc/Makefile.am
index 15a1d8b0b..843d0db2b 100644
--- a/src/misc/Makefile.am
+++ b/src/misc/Makefile.am
@@ -63,6 +63,7 @@ libmisc_la_SOURCES = \
   bddop.cc \
   escape.cc \
   freelist.cc \
+  formater.cc \
   intvcomp.cc \
   intvcmp2.cc \
   memusage.cc \
diff --git a/src/misc/formater.cc b/src/misc/formater.cc
new file mode 100644
index 000000000..68acf2fb3
--- /dev/null
+++ b/src/misc/formater.cc
@@ -0,0 +1,55 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2012 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/>.
+
+#include "formater.hh"
+#include <iostream>
+
+namespace spot
+{
+  void
+  formater::prime(const char* fmt)
+  {
+    for (const char* pos = fmt; *pos; ++pos)
+      if (*pos == '%')
+	{
+	  char c = *++pos;
+	  has_[c] = true;
+	  if (!c)
+	    break;
+	}
+  }
+
+  std::ostream&
+  formater::format(const char* fmt)
+    {
+      for (const char* pos = fmt; *pos; ++pos)
+	if (*pos != '%')
+	  {
+	    *output_ << *pos;
+	  }
+	else
+	  {
+	    char c = *++pos;
+	    call_[c]->print(*output_, pos);
+	    if (!c)
+	      break;
+	  }
+      return *output_;
+    }
+}
diff --git a/src/misc/formater.hh b/src/misc/formater.hh
index 1e7defb04..28f77bb75 100644
--- a/src/misc/formater.hh
+++ b/src/misc/formater.hh
@@ -6,7 +6,7 @@
 //
 // 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 2 of the License, or
+// 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
@@ -15,12 +15,10 @@
 // License for more details.
 //
 // You should have received a copy of the GNU General Public License
-// along with Spot; see the file COPYING.  If not, write to the Free
-// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
-// 02111-1307, USA.
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-#ifndef SPOT_SRC_MISC_FORMATER_HH
-#define SPOT_SRC_MISC_FORMATER_HH
+#ifndef SPOT_MISC_FORMATER_HH
+#define SPOT_MISC_FORMATER_HH
 
 #include <iostream>
 #include <string>
@@ -116,17 +114,7 @@ namespace spot
 
     /// Collect the %-sequences occurring in \a fmt.
     void
-    prime(const char* fmt)
-    {
-      for (const char* pos = fmt; *pos; ++pos)
-	if (*pos == '%')
-	  {
-	    char c = *++pos;
-	    has_[c] = true;
-	    if (!c)
-	      break;
-	  }
-    }
+    prime(const char* fmt);
 
     /// Collect the %-sequences occurring in \a fmt.
     void
@@ -158,22 +146,7 @@ namespace spot
 
     /// Expand the %-sequences in \a fmt, write the result on \a output_.
     std::ostream&
-    format(const char* fmt)
-    {
-      for (const char* pos = fmt; *pos; ++pos)
-	if (*pos != '%')
-	  {
-	    *output_ << *pos;
-	  }
-	else
-	  {
-	    char c = *++pos;
-	    call_[c]->print(*output_, pos);
-	    if (!c)
-	      break;
-	  }
-      return *output_;
-    }
+    format(const char* fmt);
 
     /// Expand the %-sequences in \a fmt, write the result on \a output.
     std::ostream&
@@ -207,4 +180,4 @@ namespace spot
 
 }
 
-#endif // SPOT_SRC_MISC_FORMATER_HH
+#endif // SPOT_MISC_FORMATER_HH
diff --git a/src/sanity/style.test b/src/sanity/style.test
index 6985b5e71..316f831c1 100755
--- a/src/sanity/style.test
+++ b/src/sanity/style.test
@@ -198,7 +198,7 @@ for dir in "${INCDIR-..}" "${INCDIR-..}"/../iface; do
 
       case $file in
 	*.hh | *.hxx)
-	  if egrep '(cout|cerr|clog)' $tmp >/dev/null; then
+	  if egrep '(<<|>>)' $tmp >/dev/null; then
 	    :
 	  else
 	    grep '#.*include.*<iostream>' $tmp &&