diff --git a/invenio_indexer/__init__.py b/invenio_indexer/__init__.py
index 6afa6b6..df7f12f 100644
--- a/invenio_indexer/__init__.py
+++ b/invenio_indexer/__init__.py
@@ -174,8 +174,7 @@
 from __future__ import absolute_import, print_function
 
 from .ext import InvenioIndexer
-from .version import __version__
-
 from .proxies import current_record_to_index
+from .version import __version__
 
 __all__ = ('__version__', 'InvenioIndexer', 'current_record_to_index')
diff --git a/setup.py b/setup.py
index 48a7ec8..cc14c7a 100644
--- a/setup.py
+++ b/setup.py
@@ -16,6 +16,7 @@
 history = open('CHANGES.rst').read()
 
 tests_require = [
+    'attrs>=17.4.0',
     'check-manifest>=0.25',
     'coverage>=4.0',
     'invenio-db[versioning]>=1.0.0',