diff --git a/phpBB/includes/notification/type/pm.php b/phpBB/includes/notification/type/pm.php
index 8d31c87817..b3db7ad5ad 100644
--- a/phpBB/includes/notification/type/pm.php
+++ b/phpBB/includes/notification/type/pm.php
@@ -161,7 +161,7 @@ class phpbb_notification_type_pm extends phpbb_notification_type_base
 	*/
 	public function users_to_query()
 	{
-		return array($this->data['from_user_id']);
+		return array($this->get_data('from_user_id'));
 	}
 
 	/**
diff --git a/phpBB/includes/notification/type/report_pm.php b/phpBB/includes/notification/type/report_pm.php
index 877e8209e3..3fa73bab41 100644
--- a/phpBB/includes/notification/type/report_pm.php
+++ b/phpBB/includes/notification/type/report_pm.php
@@ -205,7 +205,7 @@ class phpbb_notification_type_report_pm extends phpbb_notification_type_pm
 	*/
 	public function users_to_query()
 	{
-		return array($this->data['reporter_id']);
+		return array($this->get_data('reporter_id'));
 	}
 
 	/**
diff --git a/phpBB/includes/notification/type/report_pm_closed.php b/phpBB/includes/notification/type/report_pm_closed.php
index a735d2a822..63dfa92064 100644
--- a/phpBB/includes/notification/type/report_pm_closed.php
+++ b/phpBB/includes/notification/type/report_pm_closed.php
@@ -130,7 +130,7 @@ class phpbb_notification_type_report_pm_closed extends phpbb_notification_type_p
 	*/
 	public function users_to_query()
 	{
-		return array($this->data['closer_id']);
+		return array($this->get_data('closer_id'));
 	}
 
 	/**
diff --git a/phpBB/includes/notification/type/report_post.php b/phpBB/includes/notification/type/report_post.php
index 0334fdb109..1ea532c929 100644
--- a/phpBB/includes/notification/type/report_post.php
+++ b/phpBB/includes/notification/type/report_post.php
@@ -172,7 +172,7 @@ class phpbb_notification_type_report_post extends phpbb_notification_type_post_i
 	*/
 	public function users_to_query()
 	{
-		return array($this->data['reporter_id']);
+		return array($this->get_data('reporter_id'));
 	}
 
 	/**
diff --git a/phpBB/includes/notification/type/report_post_closed.php b/phpBB/includes/notification/type/report_post_closed.php
index 8b984fc8ce..3916cd8db7 100644
--- a/phpBB/includes/notification/type/report_post_closed.php
+++ b/phpBB/includes/notification/type/report_post_closed.php
@@ -130,7 +130,7 @@ class phpbb_notification_type_report_post_closed extends phpbb_notification_type
 	*/
 	public function users_to_query()
 	{
-		return array($this->data['closer_id']);
+		return array($this->get_data('closer_id'));
 	}
 
 	/**
diff --git a/phpBB/includes/notification/type/topic.php b/phpBB/includes/notification/type/topic.php
index 4f51ed4cb1..71e074fb50 100644
--- a/phpBB/includes/notification/type/topic.php
+++ b/phpBB/includes/notification/type/topic.php
@@ -208,7 +208,7 @@ class phpbb_notification_type_topic extends phpbb_notification_type_base
 	*/
 	public function users_to_query()
 	{
-		return array($this->data['poster_id']);
+		return array($this->get_data('poster_id'));
 	}
 
 	/**