diff --git a/platypush/backend/http/__init__.py b/platypush/backend/http/__init__.py
index 185a51d7..40e3890f 100644
--- a/platypush/backend/http/__init__.py
+++ b/platypush/backend/http/__init__.py
@@ -54,6 +54,7 @@ class HttpBackend(Backend):
         * **flask** (``pip install flask``)
         * **redis** (``pip install redis``)
         * **websockets** (``pip install websockets``)
+        * **python-dateutil** (``pip install python-dateutil``)
     """
 
     hidden_plugins = {
diff --git a/platypush/plugins/calendar/ical.py b/platypush/plugins/calendar/ical.py
index 5927a538..a5c591b8 100644
--- a/platypush/plugins/calendar/ical.py
+++ b/platypush/plugins/calendar/ical.py
@@ -20,6 +20,7 @@ class IcalCalendarPlugin(Plugin, CalendarInterface):
     Requires:
 
         * **icalendar** (``pip install icalendar``)
+        * **python-dateutil** (``pip install python-dateutil``)
     """
 
     def __init__(self, url, *args, **kwargs):
diff --git a/requirements.txt b/requirements.txt
index fbd9b549..5d4dbc0e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -18,6 +18,7 @@ websocket-client
 flask
 websockets
 redis
+python-dateutil
 
 # HTTP poll backend support
 frozendict