diff --git a/Dockerfile-reminders b/Dockerfile-reminders
index 515842b2..bc32201a 100644
--- a/Dockerfile-reminders
+++ b/Dockerfile-reminders
@@ -6,8 +6,9 @@ RUN cd /toot && cargo build
 
 FROM ruby:3-bullseye
 COPY --from=toot /toot/target/debug/toot /usr/local/bin/
-RUN gem install t
+RUN gem install t && gem install ri_cal
 COPY scripts/send-reminder-tweets.sh /usr/local/bin/
+COPY scripts/tweet-reminders.rb /usr/local/bin/
 VOLUME /data
 ENV WEBSITE_DIR=/website
 RUN useradd -M -d /data reminders && chown reminders:reminders /data
diff --git a/scripts/send-reminder-tweets.sh b/scripts/send-reminder-tweets.sh
index b42a520e..db10e047 100755
--- a/scripts/send-reminder-tweets.sh
+++ b/scripts/send-reminder-tweets.sh
@@ -6,27 +6,32 @@ if [[ -f "/usr/local/bundle/bin/t" ]] ; then
 else
   T="bundle exec t"
 fi
+if [[ -f "/usr/local/bin/tweet-reminders.rb" ]] ; then
+  REMINDERS=/usr/local/bin/tweet-reminders.rb
+else
+  REMINDERS=scripts/tweet-reminders.rb
+fi
 TOOT=${TOOT:-/usr/local/bin/toot}
 
 cd `dirname $0`/..
 
-cat "$WEBSITE_DIR/cccs.ical" | scripts/tweet-reminders.rb 0 "Heute:" | while read LINE ; do
+cat "$WEBSITE_DIR/cccs.ical" | "$REMINDERS" 0 "Heute:" | while read LINE ; do
 	$T update "$LINE"
 done
-cat "$WEBSITE_DIR/cccs.ical" | scripts/tweet-reminders.rb 1 "Morgen:" | while read LINE ; do
+cat "$WEBSITE_DIR/cccs.ical" | "$REMINDERS" 1 "Morgen:" | while read LINE ; do
 	$T update "$LINE"
 done
-cat "$WEBSITE_DIR/cccs.ical" | scripts/tweet-reminders.rb 7 "In einer Woche:" | while read LINE ; do
+cat "$WEBSITE_DIR/cccs.ical" | "$REMINDERS" 7 "In einer Woche:" | while read LINE ; do
 	$T update "$LINE"
 done
 
-cat "$WEBSITE_DIR/cccs.ical" | scripts/tweet-reminders.rb 0 "Heute:" 500 | while read LINE ; do
+cat "$WEBSITE_DIR/cccs.ical" | "$REMINDERS" 0 "Heute:" 500 | while read LINE ; do
 	$TOOT "$LINE"
 done
-cat "$WEBSITE_DIR/cccs.ical" | scripts/tweet-reminders.rb 1 "Morgen:" 500 | while read LINE ; do
+cat "$WEBSITE_DIR/cccs.ical" | "$REMINDERS" 1 "Morgen:" 500 | while read LINE ; do
 	$TOOT "$LINE"
 done
-cat "$WEBSITE_DIR/cccs.ical" | scripts/tweet-reminders.rb 7 "In einer Woche:" 500 | while read LINE ; do
+cat "$WEBSITE_DIR/cccs.ical" | "$REMINDERS" 7 "In einer Woche:" 500 | while read LINE ; do
 	$TOOT "$LINE"
 done