diff --git a/setup/mail-dovecot.sh b/setup/mail-dovecot.sh
index a4bb563b..8d45a50b 100755
--- a/setup/mail-dovecot.sh
+++ b/setup/mail-dovecot.sh
@@ -202,13 +202,13 @@ chmod -R o-rwx /etc/dovecot
 
 # Ensure mailbox files have a directory that exists and are owned by the mail user.
 mkdir -p $STORAGE_ROOT/mail/mailboxes
-chown -R mail.mail $STORAGE_ROOT/mail/mailboxes
+chown -R mail:mail $STORAGE_ROOT/mail/mailboxes
 
 # Same for the sieve scripts.
 mkdir -p $STORAGE_ROOT/mail/sieve
 mkdir -p $STORAGE_ROOT/mail/sieve/global_before
 mkdir -p $STORAGE_ROOT/mail/sieve/global_after
-chown -R mail.mail $STORAGE_ROOT/mail/sieve
+chown -R mail:mail $STORAGE_ROOT/mail/sieve
 
 # Allow the IMAP/POP ports in the firewall.
 ufw_allow imaps
diff --git a/setup/munin.sh b/setup/munin.sh
index 6799cad6..90f93521 100755
--- a/setup/munin.sh
+++ b/setup/munin.sh
@@ -34,8 +34,8 @@ contact.admin.always_send warning critical
 EOF
 
 # The Debian installer touches these files and chowns them to www-data:adm for use with spawn-fcgi
-chown munin. /var/log/munin/munin-cgi-html.log
-chown munin. /var/log/munin/munin-cgi-graph.log
+chown munin /var/log/munin/munin-cgi-html.log
+chown munin /var/log/munin/munin-cgi-graph.log
 
 # ensure munin-node knows the name of this machine
 # and reduce logging level to warning
diff --git a/setup/nextcloud.sh b/setup/nextcloud.sh
index 13afc6b7..50d1130a 100755
--- a/setup/nextcloud.sh
+++ b/setup/nextcloud.sh
@@ -110,7 +110,7 @@ InstallNextcloud() {
 	# Make sure permissions are correct or the upgrade step won't run.
 	# $STORAGE_ROOT/owncloud may not yet exist, so use -f to suppress
 	# that error.
-	chown -f -R www-data.www-data $STORAGE_ROOT/owncloud /usr/local/lib/owncloud || /bin/true
+	chown -f -R www-data:www-data $STORAGE_ROOT/owncloud /usr/local/lib/owncloud || /bin/true
 
 	# If this isn't a new installation, immediately run the upgrade script.
 	# Then check for success (0=ok and 3=no upgrade needed, both are success).
@@ -259,7 +259,7 @@ EOF
 EOF
 
 	# Set permissions
-	chown -R www-data.www-data $STORAGE_ROOT/owncloud /usr/local/lib/owncloud
+	chown -R www-data:www-data $STORAGE_ROOT/owncloud /usr/local/lib/owncloud
 
 	# Execute Nextcloud's setup step, which creates the Nextcloud sqlite database.
 	# It also wipes it if it exists. And it updates config.php with database
@@ -311,7 +311,7 @@ var_export(\$CONFIG);
 echo ";";
 ?>
 EOF
-chown www-data.www-data $STORAGE_ROOT/owncloud/config.php
+chown www-data:www-data $STORAGE_ROOT/owncloud/config.php
 
 # Enable/disable apps. Note that this must be done after the Nextcloud setup.
 # The firstrunwizard gave Josh all sorts of problems, so disabling that.
diff --git a/setup/start.sh b/setup/start.sh
index 0626ab01..960ec55d 100755
--- a/setup/start.sh
+++ b/setup/start.sh
@@ -85,7 +85,7 @@ f=$STORAGE_ROOT
 while [[ $f != / ]]; do chmod a+rx "$f"; f=$(dirname "$f"); done;
 if [ ! -f $STORAGE_ROOT/mailinabox.version ]; then
 	setup/migrate.py --current > $STORAGE_ROOT/mailinabox.version
-	chown $STORAGE_USER.$STORAGE_USER $STORAGE_ROOT/mailinabox.version
+	chown $STORAGE_USER:$STORAGE_USER $STORAGE_ROOT/mailinabox.version
 fi
 
 # Save the global options in /etc/mailinabox.conf so that standalone
diff --git a/setup/webmail.sh b/setup/webmail.sh
index 90e97aed..274f7506 100755
--- a/setup/webmail.sh
+++ b/setup/webmail.sh
@@ -170,7 +170,7 @@ EOF
 
 # Create writable directories.
 mkdir -p /var/log/roundcubemail /var/tmp/roundcubemail $STORAGE_ROOT/mail/roundcube
-chown -R www-data.www-data /var/log/roundcubemail /var/tmp/roundcubemail $STORAGE_ROOT/mail/roundcube
+chown -R www-data:www-data /var/log/roundcubemail /var/tmp/roundcubemail $STORAGE_ROOT/mail/roundcube
 
 # Ensure the log file monitored by fail2ban exists, or else fail2ban can't start.
 sudo -u www-data touch /var/log/roundcubemail/errors.log
@@ -194,14 +194,14 @@ usermod -a -G dovecot www-data
 
 # set permissions so that PHP can use users.sqlite
 # could use dovecot instead of www-data, but not sure it matters
-chown root.www-data $STORAGE_ROOT/mail
+chown root:www-data $STORAGE_ROOT/mail
 chmod 775 $STORAGE_ROOT/mail
-chown root.www-data $STORAGE_ROOT/mail/users.sqlite
+chown root:www-data $STORAGE_ROOT/mail/users.sqlite
 chmod 664 $STORAGE_ROOT/mail/users.sqlite
 
 # Fix Carddav permissions:
-chown -f -R root.www-data ${RCM_PLUGIN_DIR}/carddav
-# root.www-data need all permissions, others only read
+chown -f -R root:www-data ${RCM_PLUGIN_DIR}/carddav
+# root:www-data need all permissions, others only read
 chmod -R 774 ${RCM_PLUGIN_DIR}/carddav
 
 # Run Roundcube database migration script (database is created if it does not exist)
diff --git a/tools/owncloud-restore.sh b/tools/owncloud-restore.sh
index 108c8b77..cdeec4e9 100755
--- a/tools/owncloud-restore.sh
+++ b/tools/owncloud-restore.sh
@@ -40,8 +40,8 @@ cp "$1/owncloud.db" $STORAGE_ROOT/owncloud/
 cp "$1/config.php" $STORAGE_ROOT/owncloud/
 
 ln -sf $STORAGE_ROOT/owncloud/config.php /usr/local/lib/owncloud/config/config.php
-chown -f -R www-data.www-data $STORAGE_ROOT/owncloud /usr/local/lib/owncloud
-chown www-data.www-data $STORAGE_ROOT/owncloud/config.php
+chown -f -R www-data:www-data $STORAGE_ROOT/owncloud /usr/local/lib/owncloud
+chown www-data:www-data $STORAGE_ROOT/owncloud/config.php
 
 sudo -u www-data php$PHP_VER /usr/local/lib/owncloud/occ maintenance:mode --off