diff --git a/README.md b/README.md
index ccf3782..f24ca20 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,28 @@ configuration file in `/etc/borgwrapper/<config_name>` do:
     systemctl start borgwrapper-backup@<config_name>.timer
     systemctl start borgwrapper-verify@<config_name>.timer
 
+The included systemd files are set up using a daily schedule. If you want to
+take backups more often than that you can either change the `Timer` parameters
+directly in the systemd timer files, or if you only want to override them for
+some of the backups you can add per-config overrides by using
+
+    systemctl edit borgwrapper-backup@<config>
+
+and add the wanted overrides. Here is an example where you run a backup 4 times
+a day (every 6 hours). See the manual for systemd.timer for more information on
+the `OnCalendar` format.
+
+    [Timer]
+    OnCalendar=00/6:00
+    RandomizedDelaySec=0
+
+The output will land in
+
+    /etc/systemd/system/borgwrapper-backup@<config>.timer.d/override.conf
+
+You can just drop files in the directory directly too, without editing via
+systemctl. This is better suited for configuration management systems.
+
 You can view the backup logs with:
 
     journalctl -xu borgwrapper-backup@<config_name>
diff --git a/src/borgwrapper b/src/borgwrapper
index e33d18b..b1f3166 100755
--- a/src/borgwrapper
+++ b/src/borgwrapper
@@ -86,10 +86,11 @@ borg_prune () {
     ${BORG} prune \
         "${BORG_PRUNE_ARGS[@]}" \
         --prefix "{hostname}-" \
-        --keep-daily=${KEEP_DAILY} \
-        --keep-weekly=${KEEP_WEEKLY} \
-        --keep-monthly=${KEEP_MONTHLY} \
-        --keep-yearly=${KEEP_YEARLY} \
+        --keep-hourly=${KEEP_HOURLY:-0} \
+        --keep-daily=${KEEP_DAILY:-0} \
+        --keep-weekly=${KEEP_WEEKLY:-0} \
+        --keep-monthly=${KEEP_MONTHLY:-0} \
+        --keep-yearly=${KEEP_YEARLY:-0} \
         "${BORG_REPO}"
 }
 
diff --git a/src/config.example b/src/config.example
index 7924c37..052d37c 100644
--- a/src/config.example
+++ b/src/config.example
@@ -17,6 +17,7 @@ EXCLUDES=(
     "/root/.cache"
     "*.pyc"
 )
+KEEP_HOURLY=0
 KEEP_DAILY=31
 KEEP_WEEKLY=0
 KEEP_MONTHLY=24