diff --git a/Dockerfile b/Dockerfile
index 2401328..35917a1 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -21,6 +21,8 @@ RUN apt-get update \
 	&& rm -f /etc/cron.d/* \
 	# Install plugin dependencies \
 	&& bundle check || bundle install \
+	#  (for hourglass plugin) \
+	&& bundle exec rake redmine:plugins:assets RAILS_ENV=production \
 	&& chmod +x /pre-entrypoint.sh \
 	# setting ENTRYPOINT destroys CMD so replace the entrypoint script and call it later \
 	# (see bottom note in https://docs.docker.com/engine/reference/builder/#entrypoint) \