diff --git a/install_roundcube.sh b/install_roundcube.sh
index 0fc7cd1..f4b0894 100755
--- a/install_roundcube.sh
+++ b/install_roundcube.sh
@@ -303,7 +303,7 @@ elif [[ -f "/etc/mysql/debian.cnf" ]] ; then
 else
    DEFAULT_MYSQL_CREDENTIALS=""
 fi
-DEFAULT_DEBIAN_MYSQL_CREDENTIALS="/etc/mysql/debian.cnf"
+DEFAULT_DEBIAN_MYSQL_CREDENTIALS="--defaults-file=/etc/mysql/debian.cnf"
 
 [[ -n "$ROUNDCUBE_VERSION" ]] || fatal "Roundcube Version (ROUNDCUBE_VERSION) not present!"
 [[ -n "$WEBSITE_NAME" ]] || fatal "Website's name (WEBSITE_NAME) not present!"