diff --git a/Makefile b/Makefile
index 414fe6d..90a3fdb 100644
--- a/Makefile
+++ b/Makefile
@@ -1,11 +1,11 @@
 test: flake8 pylint pytest
 
 flake8:
-	flake8 nameko_sqlalchemy.py test
+	flake8 nameko_sqlalchemy test
 
 pylint:
 	pylint nameko_sqlalchemy -E
 
 pytest:
-	coverage run --concurrency=eventlet --source nameko_sqlalchemy.py --branch -m pytest test
+	coverage run --concurrency=eventlet --source nameko_sqlalchemy --branch -m pytest test
 	coverage report --show-missing --fail-under=100
diff --git a/nameko_sqlalchemy/__init__.py b/nameko_sqlalchemy/__init__.py
new file mode 100644
index 0000000..61e7828
--- /dev/null
+++ b/nameko_sqlalchemy/__init__.py
@@ -0,0 +1,3 @@
+from nameko_sqlalchemy.database_session import (  # noqa: F401
+    DatabaseSession, DB_URIS_KEY, Session
+)
diff --git a/nameko_sqlalchemy.py b/nameko_sqlalchemy/database_session.py
similarity index 100%
rename from nameko_sqlalchemy.py
rename to nameko_sqlalchemy/database_session.py
diff --git a/pytest_fixtures.py b/nameko_sqlalchemy/pytest_fixtures.py
similarity index 88%
rename from pytest_fixtures.py
rename to nameko_sqlalchemy/pytest_fixtures.py
index d6ac5a3..23d16f2 100644
--- a/pytest_fixtures.py
+++ b/nameko_sqlalchemy/pytest_fixtures.py
@@ -1,7 +1,6 @@
 import pytest
 
 from sqlalchemy import create_engine
-from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker
 
 
@@ -38,13 +37,10 @@ def db_url(request):
 
 @pytest.fixture(scope='session')
 def model_base():
-    """ Returns `sqlalchemy.ext.declarative.declarative_base` used
-    for declarative database definitions
+    """Override this fixture to return declarative base of your model
 
     http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/api.html
 
-    You need to override this fixture to return declarative base of your model:
-
     .. code-block:: python
 
         from sqlalchemy.ext.declarative import declarative_base
@@ -63,7 +59,7 @@ class User(DeclarativeBase):
         def model_base():
             return DeclarativeBase
     """
-    return declarative_base()
+    raise NotImplementedError("Fixture `model_base` has to be overwritten")
 
 
 @pytest.yield_fixture(scope='session')
diff --git a/setup.py b/setup.py
index 1ab08c4..d616eca 100644
--- a/setup.py
+++ b/setup.py
@@ -8,7 +8,7 @@
     author='onefinestay',
     author_email='engineering@onefinestay.com',
     url='http://github.com/onefinestay/nameko-sqlalchemy',
-    py_modules=['nameko_sqlalchemy'],
+    packages=['nameko_sqlalchemy'],
     install_requires=[
         "nameko>=2.0.0",
         "sqlalchemy"
@@ -23,7 +23,7 @@
     },
     entry_points={
         'pytest11': [
-            'pytest_fixtures=pytest_fixtures'
+            'nameko_sqlalchemy=nameko_sqlalchemy.pytest_fixtures'
         ]
     },
     zip_safe=True,
diff --git a/test/test_pytest_fixtures.py b/test/test_pytest_fixtures.py
index 5af2e53..3bc47ce 100644
--- a/test/test_pytest_fixtures.py
+++ b/test/test_pytest_fixtures.py
@@ -3,6 +3,8 @@
 from sqlalchemy import Column, Integer, String
 from sqlalchemy.ext.declarative import declarative_base
 
+pytest_plugins = "pytester"
+
 
 class Base(object):
     pass
@@ -34,3 +36,18 @@ def test_can_save_model(db_session):
 
 def test_db_is_empty(db_session):
     assert not db_session.query(User).all()
+
+
+def test_requires_override_model_base(testdir):
+
+    testdir.makepyfile(
+        """
+        def test_model_base(model_base):
+            pass
+        """
+    )
+    result = testdir.runpytest()
+    assert result.ret == 1
+    result.stdout.fnmatch_lines(
+        ["*NotImplementedError*"]
+    )