diff --git a/tests/mention/controller_test.php b/tests/mention/controller_test.php
index 4294e7365d..f3ed3babd1 100644
--- a/tests/mention/controller_test.php
+++ b/tests/mention/controller_test.php
@@ -34,7 +34,7 @@ class phpbb_mention_controller_test extends phpbb_database_test_case
 		return $this->createXMLDataSet(dirname(__FILE__) . '/fixtures/mention.xml');
 	}
 
-	public function setUp()
+	public function setUp(): void
 	{
 		parent::setUp();
 
diff --git a/tests/notification/submit_post_type_mention_test.php b/tests/notification/submit_post_type_mention_test.php
index 642ef83ec3..f660a38ecc 100644
--- a/tests/notification/submit_post_type_mention_test.php
+++ b/tests/notification/submit_post_type_mention_test.php
@@ -17,7 +17,7 @@ class phpbb_notification_submit_post_type_mention_test extends phpbb_notificatio
 {
 	protected $item_type = 'notification.type.mention';
 
-	public function setUp()
+	public function setUp(): void
 	{
 		parent::setUp();
 
diff --git a/tests/text_formatter/s9e/mention_helper_test.php b/tests/text_formatter/s9e/mention_helper_test.php
index 0665cd3ce5..e0293c9747 100644
--- a/tests/text_formatter/s9e/mention_helper_test.php
+++ b/tests/text_formatter/s9e/mention_helper_test.php
@@ -27,7 +27,7 @@ class mention_helper_test extends phpbb_database_test_case
 		return $this->createXMLDataSet(dirname(__FILE__) . '/fixtures/mention.xml');
 	}
 
-	public function setUp()
+	public function setUp(): void
 	{
 		parent::setUp();