diff --git a/permissions/forms.py b/permissions/forms.py
index 0de7d13..3ee46e2 100644
--- a/permissions/forms.py
+++ b/permissions/forms.py
@@ -62,7 +62,9 @@ class ProjectPermissionForm(PermissionForm):
 
     class Meta:
         model = ProjectPermission
-        fields =  [ 'grantee_type', 'grantee_id' ]
+        # project is required for the unicity check
+        fields =  [ 'project', 'grantee_type', 'grantee_id' ]
         widgets = {
+            'project': HiddenInput,
             'grantee_id': HiddenInput,
         }
diff --git a/permissions/models.py b/permissions/models.py
index be11fcb..6061012 100644
--- a/permissions/models.py
+++ b/permissions/models.py
@@ -82,7 +82,7 @@ class PermissionModel(models.Model):
 class GlobalPermission(PermissionModel):
 
     class Meta:
-        unique_together = [ 'grantee_type', 'grantee_id' ]
+        unique_together = ( 'grantee_type', 'grantee_id' )
 
     # Global permissions
 
@@ -120,10 +120,9 @@ class GlobalPermission(PermissionModel):
 class ProjectPermission(PermissionModel):
 
     class Meta:
-        unique_together = [ 'project', 'grantee_type', 'grantee_id' ]
+        unique_together = ( 'project', 'grantee_type', 'grantee_id' )
 
-    project = models.ForeignKey(Project, editable=False,
-            related_name='permissions')
+    project = models.ForeignKey(Project, related_name='permissions')
 
     manage_project_permission = models.BooleanField(default=False)
 
diff --git a/permissions/views.py b/permissions/views.py
index 1250690..556a791 100644
--- a/permissions/views.py
+++ b/permissions/views.py
@@ -82,7 +82,8 @@ def project_perm_edit(request, project, id=None):
         perm = get_object_or_404(ProjectPermission, project=project, id=id)
     else:
         perm = None
-    form = ProjectPermissionForm(request.POST or None, instance=perm)
+    form = ProjectPermissionForm(request.POST or None, instance=perm,
+            initial={'project': project.id})
     if request.method == 'POST' and form.is_valid():
         if id:
             form.save()
diff --git a/templates/permissions/project_perm_edit.html b/templates/permissions/project_perm_edit.html
index 88b346f..935340f 100644
--- a/templates/permissions/project_perm_edit.html
+++ b/templates/permissions/project_perm_edit.html
@@ -32,6 +32,7 @@
     <form method="post" role="form">
       {% csrf_token %}
       {% bootstrap_form_errors form %}
+      {% bootstrap_field form.project %}
       {% bootstrap_field form.grantee_type %}
       {% bootstrap_field form.grantee_id %}
       <div class="form-group">