diff --git a/en_US/howto/1-completely.disable.amavisd.clamav.spamassassin.md b/en_US/howto/1-completely.disable.amavisd.clamav.spamassassin.md
index 33775d5f..bd69c61d 100644
--- a/en_US/howto/1-completely.disable.amavisd.clamav.spamassassin.md
+++ b/en_US/howto/1-completely.disable.amavisd.clamav.spamassassin.md
@@ -33,11 +33,13 @@ Uncomment above lines (removing "# " at the beginning of each line), and restart
You may want to stop and disable ClamAV service too since it's not
called by Amavisd or other programs anymore:
-```
-# CentOS
-systemctl disable --now clamd@amavisd
-systemctl restart amavisd
+ On CentOS, the systemd script for Amavisd service
+ (`/lib/systemd/system/amavisd.service`) has line
+ `Wants=clamd@amavisd.service`, this makes systemd to start `clamd@amavisd`
+ service each time before starting `amavisd` service, so you have to comment
+ out this line to disable clamav service.
+```
# Debian/Ubuntu
systemctl disable --now clamav-daemon
systemctl restart amavis
diff --git a/html/completely.disable.amavisd.clamav.spamassassin.html b/html/completely.disable.amavisd.clamav.spamassassin.html
index 1ad860ab..4a2fb25e 100644
--- a/html/completely.disable.amavisd.clamav.spamassassin.html
+++ b/html/completely.disable.amavisd.clamav.spamassassin.html
@@ -61,11 +61,13 @@
Uncomment above lines (removing "# " at the beginning of each line), and restart Amavisd service.
You may want to stop and disable ClamAV service too since it's not
called by Amavisd or other programs anymore:
-# CentOS
-systemctl disable --now clamd@amavisd
-systemctl restart amavisd
-
-# Debian/Ubuntu
+On CentOS, the systemd script for Amavisd service
+(`/lib/systemd/system/amavisd.service`) has line
+`Wants=clamd@amavisd.service`, this makes systemd to start `clamd@amavisd`
+service each time before starting `amavisd` service, so you have to comment
+out this line to disable clamav service.
+
+# Debian/Ubuntu
systemctl disable --now clamav-daemon
systemctl restart amavis