diff --git a/library/Icingadb/Common/Backend.php b/library/Icingadb/Common/Backend.php
index 15cb93cc..26d52f0c 100644
--- a/library/Icingadb/Common/Backend.php
+++ b/library/Icingadb/Common/Backend.php
@@ -15,6 +15,7 @@ use ipl\Sql\Expression;
 use ipl\Sql\QueryBuilder;
 use ipl\Sql\Select;
 use PDO;
+use Pdo\Mysql;
 
 /**
  * Singleton providing access to the Icinga DB and Redis
@@ -61,7 +62,8 @@ final class Backend
 
             $config->options = [PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_OBJ];
             if ($config->db === 'mysql') {
-                $config->options[PDO::MYSQL_ATTR_INIT_COMMAND] = "SET SESSION SQL_MODE='STRICT_TRANS_TABLES"
+                $config->options[Mysql::ATTR_INIT_COMMAND]
+                    = "SET SESSION SQL_MODE='STRICT_TRANS_TABLES"
                     . ",NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION'";
             }