diff --git a/machines/forms.py b/machines/forms.py
index 0de53c49..9f5a96ca 100644
--- a/machines/forms.py
+++ b/machines/forms.py
@@ -110,11 +110,11 @@ class DomainForm(AliasForm):
         fields = ['name']
 
     def __init__(self, *args, **kwargs):
-        if 'name_user' in kwargs:
-            name_user = kwargs.pop('name_user')
+        if 'user' in kwargs:
+            user = kwargs.pop('user')
             nb_machine = kwargs.pop('nb_machine')
             initial = kwargs.get('initial', {})
-            initial['name'] = name_user.lower()+str(nb_machine)
+            initial['name'] = user.get_next_domain_name()
             kwargs['initial'] = initial 
         super(DomainForm, self).__init__(*args, **kwargs)
  
diff --git a/machines/views.py b/machines/views.py
index 4268519b..9fc64236 100644
--- a/machines/views.py
+++ b/machines/views.py
@@ -93,7 +93,7 @@ def new_machine(request, userid):
     machine = NewMachineForm(request.POST or None)
     interface = AddInterfaceForm(request.POST or None, infra=request.user.has_perms(('infra',))) 
     nb_machine = Interface.objects.filter(machine__user=userid).count()
-    domain = DomainForm(request.POST or None, name_user=user.pseudo.replace('_','-'), nb_machine=nb_machine)
+    domain = DomainForm(request.POST or None, user=user, nb_machine=nb_machine)
     if machine.is_valid() and interface.is_valid():
         new_machine = machine.save(commit=False)
         new_machine.user = user
diff --git a/users/models.py b/users/models.py
index a69493ae..61c39aad 100644
--- a/users/models.py
+++ b/users/models.py
@@ -50,7 +50,7 @@ from django.contrib.auth.models import AbstractBaseUser, BaseUserManager
 from django.core.validators import MinLengthValidator
 from topologie.models import Room
 from cotisations.models import Cotisation, Facture, Paiement, Vente
-from machines.models import Domain, Interface, MachineType, Machine, Nas, MachineType, regen
+from machines.models import Domain, Interface, MachineType, Machine, Nas, MachineType, Extension, regen
 from preferences.models import GeneralOption, AssoOption, OptionalUser, OptionalMachine, MailMessageOption
 
 now = timezone.now()
@@ -473,7 +473,7 @@ class User(AbstractBaseUser):
             interface_cible.clean()
             machine_parent.clean()
             domain = Domain()
-            domain.name = self.pseudo.replace('_','-').lower() + str(all_machines.count())
+            domain.name = self.get_next_domain_name()
             domain.interface_parent = interface_cible
             domain.clean()
             machine_parent.save()
@@ -494,6 +494,23 @@ class User(AbstractBaseUser):
         self.pwd_ntlm = hashNT(password)
         return
 
+    def get_next_domain_name(self):
+        """Look for an available name for a new interface for
+        this user by trying "pseudo0", "pseudo1", "pseudo2", ...
+        """
+
+        def simple_pseudo():
+            return self.pseudo.replace('_', '-').lower()
+
+        def composed_pseudo( n ):
+            return simple_pseudo() + str(n)
+
+        num = 0
+        while Domain.objects.filter(name=composed_pseudo(num)) :
+            num += 1
+        return composed_pseudo(num)
+
+
     def __str__(self):
         return self.pseudo