diff --git a/__init__.py b/__init__.py
index f646784..e3b55ee 100644
--- a/__init__.py
+++ b/__init__.py
@@ -1,15 +1,15 @@
 # The COPYRIGHT file at the top level of this repository contains the full
 # copyright notices and license terms.
 from trytond.pool import Pool
-from .production import *
+from . import production
 
 
 def register():
     Pool.register(
-        BOMTree,
-        OpenBOMTreeStart,
-        OpenBOMTreeTree,
+        production.BOMTree,
+        production.OpenBOMTreeStart,
+        production.OpenBOMTreeTree,
         module='production_bom_stock_form', type_='model')
     Pool.register(
-        OpenBOMTree,
+        production.OpenBOMTree,
         module='production_bom_stock_form', type_='wizard')
diff --git a/tryton.cfg b/tryton.cfg
index 6dfa11a..b2ff027 100644
--- a/tryton.cfg
+++ b/tryton.cfg
@@ -1,5 +1,5 @@
 [tryton]
-version=3.4.0
+version=4.0
 depends:
     production
     stock_calculation