diff --git a/roles/debian/clamav/defaults/main.yml b/roles/debian/clamav/defaults/main.yml
index 4706b665f..de2ee3029 100644
--- a/roles/debian/clamav/defaults/main.yml
+++ b/roles/debian/clamav/defaults/main.yml
@@ -12,12 +12,12 @@ clamav:
   # scheduled scans, set to an empty list for no timers
   timers:
     - clamscan_daily:
-        timer_command: /usr/local/clamav/script/clamscan_daily # path to clamscan wrapper script, ensure it is defined in clamav.scripts
-        timer_OnCalendar: "*-*-* 02:30:00" # see systemd.time documentation - https://www.freedesktop.org/software/systemd/man/latest/systemd.time.html#Calendar%20Events
-  server_name: "{{ inventory_hostname }}" # for identification via email, defaults to Ansible inventory name.
+        timer_command: /usr/bin/flock -n /var/run/clamscan.lock -c /usr/local/clamav/script/clamscan_daily  # command to run clamscan wrapper script, ensure script location is defined in clamav.scripts
+        timer_OnCalendar: "*-*-* 02:30:00"  # see systemd.time documentation - https://www.freedesktop.org/software/systemd/man/latest/systemd.time.html#Calendar%20Events
+  server_name: "{{ inventory_hostname }}"  # for identification via email, defaults to Ansible inventory name.
   log_location: /var/log/clamav
-  send_mail: false # Important - will not send any emails by default.
-  send_on_fail: true # Only sends emails on scan failure, will not email for successful scans.
+  send_mail: false    # Important - will not send any emails by default.
+  send_on_fail: true  # Only sends emails on scan failure, will not email for successful scans.
   report_recipient_email: mail@example.com
   report_sender_email: admin@server.example.com
-  install_clamdscan: false # flag to install additional 'clamdscan' package
+  install_clamdscan: false  # flag to install additional 'clamdscan' package