diff --git a/lib/Cron/Workers/SubscribersStatsReport.php b/lib/Cron/Workers/SubscribersStatsReport.php
index 57835b3f2b..bcf864b1a7 100644
--- a/lib/Cron/Workers/SubscribersStatsReport.php
+++ b/lib/Cron/Workers/SubscribersStatsReport.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 namespace MailPoet\Cron\Workers;
 
diff --git a/tests/integration/Cron/Workers/SubscribersStatsReportTest.php b/tests/integration/Cron/Workers/SubscribersStatsReportTest.php
index d78fd87ac1..d29b6f7ff2 100644
--- a/tests/integration/Cron/Workers/SubscribersStatsReportTest.php
+++ b/tests/integration/Cron/Workers/SubscribersStatsReportTest.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 namespace MailPoet\Cron\Workers;