diff --git a/.drone.yml b/.drone.yml
index a4d2595986..9d7c769d8c 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -4,6 +4,6 @@ env:
   - MYSQL_URI=mysql://root@127.0.0.1:3306/
 script:
   - pip install tox
-  - tox -e sqlite,postgresql
+  - tox -e "py27-{sqlite,postgresql}"
 services:
   - postgres
diff --git a/setup.py b/setup.py
index 48732ca643..ba8b443c95 100644
--- a/setup.py
+++ b/setup.py
@@ -91,6 +91,8 @@ setup(name=name,
         'Natural Language :: Spanish',
         'Operating System :: OS Independent',
         'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: Implementation :: CPython',
+        'Programming Language :: Python :: Implementation :: PyPy',
         'Topic :: Office/Business',
         'Topic :: Office/Business :: Financial :: Accounting',
         ],
diff --git a/tox.ini b/tox.ini
index e213af00e6..e9d2876444 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,10 +1,11 @@
 [tox]
-envlist = py27-{sqlite,postgresql,mysql}
+envlist = py27-{sqlite,postgresql,mysql},pypy-{sqlite,postgresql}
 
 [testenv]
 commands = {envpython} setup.py test
 deps =
-    postgresql: psycopg2 >= 2.0
+    py27-postgresql: psycopg2 >= 2.0
+    pypy-postgresql: psycopg2cffi >= 2.5
     mysql: MySQL-python
 setenv =
     sqlite: TRYTOND_DATABASE_URI={env:SQLITE_URI:sqlite://}