diff --git a/trytond/ir/translation.py b/trytond/ir/translation.py
index 7f0a0f43ab..64c11a7036 100644
--- a/trytond/ir/translation.py
+++ b/trytond/ir/translation.py
@@ -65,6 +65,12 @@ class Translation(ModelSQL, ModelView, Cacheable):
                 'UNIQUE (name, res_id, lang, type, src, module)',
                 'Translation must be unique'),
         ]
+        self._constraints += [
+            ('check_unique_model', 'unique_model'),
+        ]
+        self._error_messages.update({
+            'unique_model': "Translation of type 'model' must be unique!",
+            })
         self._max_len = 10240
 
     def init(self, module_name):
@@ -77,6 +83,20 @@ class Translation(ModelSQL, ModelView, Cacheable):
     def default_fuzzy(self):
         return False
 
+    def check_unique_model(self, ids):
+        "Check unique model"
+        cursor = Transaction().cursor
+        query = ('SELECT count(1) FROM "%s" '
+                'WHERE type = %%s '
+                    'AND res_id != 0 '
+                'GROUP BY name, res_id, lang, type, src '
+                'HAVING count(1) > 1' % self._table)
+        cursor.execute(query, ('model',))
+        rowcount = cursor.rowcount
+        if rowcount == -1 or rowcount is None:
+            rowcount = len(cursor.fetchall())
+        return not bool(rowcount)
+
     def get_model(self, ids, name):
         res = {}
         for translation in self.browse(ids):
@@ -168,6 +188,9 @@ class Translation(ModelSQL, ModelView, Cacheable):
         model_fields_obj = self.pool.get('ir.model.field')
         model_obj = self.pool.get('ir.model')
 
+        if lang == 'en_US':
+            return 0
+
         model_name, field_name = name.split(',')
         if model_name in ('ir.model.field', 'ir.model'):
             if model_name == 'ir.model.field':
diff --git a/trytond/modules/__init__.py b/trytond/modules/__init__.py
index b9e5a08d18..d2a8e828f5 100644
--- a/trytond/modules/__init__.py
+++ b/trytond/modules/__init__.py
@@ -412,7 +412,8 @@ def load_modules(database_name, pool, update=False, lang=None):
         contextmanager = Transaction().start(database_name, 0)
     else:
         contextmanager = contextlib.nested(Transaction().new_cursor(),
-                Transaction().set_user(0))
+                Transaction().set_user(0),
+                Transaction().set_context(language='en_US'))
     with contextmanager:
         cursor = Transaction().cursor
         force = []