diff --git a/runbot/models/branch.py b/runbot/models/branch.py
index 098baeeb..f2faf988 100644
--- a/runbot/models/branch.py
+++ b/runbot/models/branch.py
@@ -135,7 +135,7 @@ class runbot_branch(models.Model):
             return False
         return True
 
-    @api.model
+    @api.model_create_single
     def create(self, vals):
         if not vals.get('config_id') and ('use-coverage' in (vals.get('name') or '')):
             coverage_config = self.env.ref('runbot.runbot_build_config_test_coverage', raise_if_not_found=False)
diff --git a/runbot/models/build.py b/runbot/models/build.py
index 2ee8d985..1378482c 100644
--- a/runbot/models/build.py
+++ b/runbot/models/build.py
@@ -198,6 +198,7 @@ class runbot_build(models.Model):
     def copy(self, values=None):
         raise UserError("Cannot duplicate build!")
 
+    @api.model_create_single
     def create(self, vals):
         branch = self.env['runbot.branch'].search([('id', '=', vals.get('branch_id', False))])  # branche 10174?
         if branch.no_build:
diff --git a/runbot/models/build_config.py b/runbot/models/build_config.py
index 17700158..08fe2da0 100644
--- a/runbot/models/build_config.py
+++ b/runbot/models/build_config.py
@@ -32,7 +32,7 @@ class Config(models.Model):
     group = fields.Many2one('runbot.build.config', 'Configuration group', help="Group of config's and config steps")
     group_name = fields.Char('Group name', related='group.name')
 
-    @api.model
+    @api.model_create_single
     def create(self, values):
         res = super(Config, self).create(values)
         res._check_step_ids_order()
@@ -163,7 +163,7 @@ class ConfigStep(models.Model):
         copy._write({'protected': False})
         return copy
 
-    @api.model
+    @api.model_create_single
     def create(self, values):
         self._check(values)
         return super(ConfigStep, self).create(values)
@@ -574,7 +574,7 @@ class ConfigStepOrder(models.Model):
     def _onchange_step_id(self):
         self.sequence = self.step_id.default_sequence
 
-    @api.model
+    @api.model_create_single
     def create(self, values):
         if 'sequence' not in values and values.get('step_id'):
             values['sequence'] = self.env['runbot.build.config.step'].browse(values.get('step_id')).default_sequence
diff --git a/runbot/models/build_error.py b/runbot/models/build_error.py
index ab9041a9..0eb9d419 100644
--- a/runbot/models/build_error.py
+++ b/runbot/models/build_error.py
@@ -49,7 +49,7 @@ class RunbotBuildError(models.Model):
             if build_error.test_tags and '-' in build_error.test_tags:
                 raise ValidationError('Build error test_tags should not be negated')
 
-    @api.model
+    @api.model_create_single
     def create(self, vals):
         cleaners = self.env['runbot.error.regex'].search([('re_type', '=', 'cleaning')])
         content = vals.get('content')
diff --git a/runbot/models/host.py b/runbot/models/host.py
index f48c2361..46556b57 100644
--- a/runbot/models/host.py
+++ b/runbot/models/host.py
@@ -38,7 +38,7 @@ class RunboHost(models.Model):
             host.nb_testing = count_by_host_state[host.name].get('testing', 0)
             host.nb_running = count_by_host_state[host.name].get('running', 0)
 
-    @api.model
+    @api.model_create_single
     def create(self, values):
         if not 'disp_name' in values:
             values['disp_name'] = values['name']