diff --git a/debian/bluecherry.cron b/debian/bluecherry.cron
index 6fef1ea1..ed3b1866 100644
--- a/debian/bluecherry.cron
+++ b/debian/bluecherry.cron
@@ -1,3 +1,14 @@
-# m h dom mon dow user          command
-0   0  *   *   *  bluecherry    /usr/share/bluecherry/backup_db.sh
-30   0  *   *   *  bluecherry    curl -k https://localhost:7001/subdomainprovidercron
+# This file is a part of bluecherry package.
+
+# .---------------- minute (0 - 59)
+# |  .------------- hour (0 - 23)
+# |  |  .---------- day of month (1 - 31)
+# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
+# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
+# |  |  |  |  |
+# *  *  *  *  *   user-name     command to be executed
+*    * */5 *  *   root          certbot renew --config-dir=/usr/share/bluecherry/nginx-includes/letsencrypt/ &> /var/log/bluecherry-letsencrypt.log
+0    0  *  *  *   bluecherry    /usr/share/bluecherry/backup_db.sh
+30   0  *  *  *   bluecherry    curl -k https://localhost:7001/subdomainprovidercron
+
+# vim: syntax=crontab
diff --git a/misc/postinstall.sh b/misc/postinstall.sh
index d1781db0..c3002254 100755
--- a/misc/postinstall.sh
+++ b/misc/postinstall.sh
@@ -158,6 +158,7 @@ function stop_apache
 # 1 - rpm install, 2 - rpm upgrade
 case "$1" in
 	configure|reconfigure|1|2)
+		PREV_INSTALLED_VERSION=$2
 		if [[ $IN_DEB ]]
 		then
 			ucfr bluecherry /etc/bluecherry.conf
@@ -446,8 +447,10 @@ case "$1" in
 
 		install_certbot
 		
-		# Install crontabs for subdomain renewal and SSL renewal using certbot
-		crontab -l 2>/dev/null || true; printf "* * */5 * * certbot renew --config-dir=/usr/share/bluecherry/nginx-includes/letsencrypt/ >/dev/null 2>&1\n*/5 * * * * curl -k https://localhost:7001/subdomainprovidercron >/dev/null 2>&1\n" | crontab -
+		# Clean root's crontab from entries which we previously put there
+		# FIXME one-time upgrade procedure would be nice.
+		# we have a nice way but use it only for mysql upgrades.
+		crontab -l 2>/dev/null | grep -v 'bluecherry\|subdomainprovidercron' | crontab -
 
 
 		nginx -t 2>/dev/null > /dev/null