diff --git a/requirements.txt b/requirements.txt
index 2ab84cc..96c594b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,6 @@
-pyowm==2.10.0
-Pillow==7.1.1
-ics==0.7
-feedparser==5.2.1
-python-dateutil==2.6.1
-numpy==1.18.2
+pyowm==2.10.0                   # weather
+Pillow==7.1.1                   # imaging
+icalendar==4.0.6                # iCalendar parsing
+recurring-ical-events==0.1.16b0 # parse recurring events
+feedparser==5.2.1               # parse RSS-feeds
+numpy==1.18.2                   # image pre-processing