diff --git a/setup.py b/setup.py
index 79bceaf..be8ae4d 100644
--- a/setup.py
+++ b/setup.py
@@ -6,7 +6,7 @@ shortdesc = 'iCalendar parser/generator'
 longdesc = open('README.rst').read()
 longdesc += open('CHANGES.rst').read()
 longdesc += open('LICENSE.rst').read()
-tests_require = ['unittest2', 'python-dateutil']
+tests_require = ['unittest2', 'python-dateutil==1.5']
 
 setuptools.setup(
     name='icalendar',
diff --git a/tox.ini b/tox.ini
index 9ca3a61..b7d53b4 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,6 @@
 [tox]
-envlist = py24,py27
+envlist = py24,py25,py27
+#envlist = py24,py27
 #envlist = py24,py25,py26,py27,py32
 
 [testenv]
@@ -7,7 +8,7 @@ deps =
     icalendar
     unittest2
     coverage
-    python-dateutil
+    python-dateutil==1.5
 commands =
     coverage erase
     coverage run --source=icalendar --omit=*tests* {envbindir}/unit2 discover icalendar []