diff --git a/.travis.yml b/.travis.yml
index 31fccb0..cc5e2c6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,8 @@ language: python
 sudo: false
 python:
     - 2.7
+    - 3.5
+    - 3.6
 install:
     - pip install coveralls coverage
     - pip install -U setuptools==33.1.1
diff --git a/CHANGES.rst b/CHANGES.rst
index d2b472c..a5b4495 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -6,8 +6,7 @@ Products.CMFUid Changelog
 
 - Require `Zope >= 4`.
 
-- Prepare for Python 2 / 3 compatibility.
-  [pbauer]
+- Add support for Python 3.5 and 3.6.
 
 - Adapt tests to the new indexing operations queueing.
   Part of PLIP 1343: https://github.com/plone/Products.CMFPlone/issues/1343
diff --git a/Products/CMFUid/__init__.py b/Products/CMFUid/__init__.py
index 44ee268..0badeec 100644
--- a/Products/CMFUid/__init__.py
+++ b/Products/CMFUid/__init__.py
@@ -18,9 +18,9 @@ def initialize(context):
 
     from Products.CMFCore import utils
 
-    import UniqueIdAnnotationTool
-    import UniqueIdGeneratorTool
-    import UniqueIdHandlerTool
+    from . import UniqueIdAnnotationTool
+    from . import UniqueIdGeneratorTool
+    from . import UniqueIdHandlerTool
 
     tools = (
         UniqueIdAnnotationTool.UniqueIdAnnotationTool,
diff --git a/buildout.cfg b/buildout.cfg
index 5a16c4f..c1033af 100644
--- a/buildout.cfg
+++ b/buildout.cfg
@@ -2,6 +2,11 @@
 extends = https://raw.githubusercontent.com/zopefoundation/Zope/master/versions.cfg
 develop = .
 parts = test
+extensions = mr.developer
+auto-checkout = *
+
+[sources]
+Products.ZCatalog = git https://github.com/zopefoundation/Products.ZCatalog.git branch=master
 
 [test]
 recipe = zc.recipe.testrunner
diff --git a/setup.py b/setup.py
index 85c78ca..6c88f54 100644
--- a/setup.py
+++ b/setup.py
@@ -27,7 +27,11 @@ def _read(name):
         "Framework :: Zope :: 4",
         "Intended Audience :: Developers",
         "License :: OSI Approved :: Zope Public License",
-        "Programming Language :: Python",
+        "Programming Language :: Python :: 2",
+        "Programming Language :: Python :: 2.7",
+        "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.5",
+        "Programming Language :: Python :: 3.6",
         "Topic :: Software Development",
         "Topic :: Software Development :: Libraries :: Application Frameworks",
     ],
@@ -44,7 +48,7 @@ def _read(name):
         'eggtestinfo',
     ],
     install_requires=[
-        'Products.CMFCore >= 2.4.0b3',
+        'Products.CMFCore >= 2.4.0dev',
         'Zope',
         'setuptools',
     ],
diff --git a/tox.ini b/tox.ini
index c9cba06..4d52143 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,8 @@
 [tox]
 envlist =
     py27,
+    py35,
+    py36,
     coverage-report,
 
 [testenv]
@@ -10,7 +12,8 @@ commands =
     {envbindir}/buildout -c {toxinidir}/buildout.cfg buildout:directory={envdir} buildout:develop={toxinidir}
     coverage run {envbindir}/test --all {posargs:-vc}
 deps =
-    zc.buildout
+    setuptools >= 39
+    zc.buildout >= 2.11
     coverage
 setenv =
     COVERAGE_FILE=.coverage.{envname}