diff --git a/containers/zammad-backup/Dockerfile b/containers/zammad-backup/Dockerfile
index 40aa1ea..2329663 100644
--- a/containers/zammad-backup/Dockerfile
+++ b/containers/zammad-backup/Dockerfile
@@ -19,7 +19,8 @@ LABEL org.label-schema.build-date="$BUILD_DATE" \
 
 RUN wget -q https://www.postgresql.org/media/keys/ACCC4CF8.asc -O - | apt-key add - \
     && echo "deb http://apt.postgresql.org/pub/repos/apt/ wheezy-pgdg main" >> /etc/apt/sources.list.d/postgres.list \
-    && apt-get update;apt-get -y install postgresql-client
+    && apt-get update;apt-get -y install postgresql-client \
+    && rm -rf /var/lib/apt/lists/*
 
 # create entrypoint
 COPY containers/zammad-backup/docker-entrypoint.sh /
diff --git a/containers/zammad-backup/docker-entrypoint.sh b/containers/zammad-backup/docker-entrypoint.sh
index f572c78..62e47d4 100644
--- a/containers/zammad-backup/docker-entrypoint.sh
+++ b/containers/zammad-backup/docker-entrypoint.sh
@@ -1,7 +1,6 @@
 #!/bin/bash
 
 if [ "$1" = 'zammad-backup' ]; then
-
   # wait for zammad process coming up
   until (echo > /dev/tcp/zammad-railsserver/3000) &> /dev/null; do
     echo "backup waiting for zammads railsserver to be ready..."
@@ -25,5 +24,4 @@ if [ "$1" = 'zammad-backup' ]; then
     # wait until next backup
     sleep ${BACKUP_SLEEP}
   done
-
 fi