diff --git a/src/Model/ItemDeliveryData.php b/src/Model/ItemDeliveryData.php
index 5a181eb1b1..7c64427eff 100644
--- a/src/Model/ItemDeliveryData.php
+++ b/src/Model/ItemDeliveryData.php
@@ -111,7 +111,7 @@ class ItemDeliveryData
 	 * @return bool
 	 * @throws \Exception
 	 */
-	public static function incrementQueueCount($item_id, $increment)
+	public static function incrementQueueCount(int $item_id, int $increment = 1)
 	{
 		return DBA::e('UPDATE `item-delivery-data` SET `queue_count` = `queue_count` + ? WHERE `iid` = ?', $increment, $item_id);
 	}
diff --git a/src/Protocol/Diaspora.php b/src/Protocol/Diaspora.php
index a0bb0d9fa3..87ec7d5a0c 100644
--- a/src/Protocol/Diaspora.php
+++ b/src/Protocol/Diaspora.php
@@ -55,7 +55,7 @@ class Diaspora
 	 *
 	 * @param array $contact of the relay contact
 	 */
-	public static function markRelayForArchival($contact)
+	public static function markRelayForArchival(array $contact)
 	{
 		if (!empty($contact['contact-type']) && ($contact['contact-type'] == Contact::TYPE_RELAY)) {
 			// This is already the relay contact, we don't need to fetch it
@@ -174,7 +174,7 @@ class Diaspora
 	 * @return array with the contact
 	 * @throws \Exception
 	 */
-	private static function getRelayContact($server_url, $fields = ['batch', 'id', 'name', 'network', 'protocol', 'archive', 'blocked'])
+	private static function getRelayContact(string $server_url, array $fields = ['batch', 'id', 'name', 'network', 'protocol', 'archive', 'blocked'])
 	{
 		// Fetch the relay contact
 		$condition = ['uid' => 0, 'nurl' => Strings::normaliseLink($server_url),
diff --git a/src/Worker/Delivery.php b/src/Worker/Delivery.php
index 3079adecc2..d29ec7c4c8 100644
--- a/src/Worker/Delivery.php
+++ b/src/Worker/Delivery.php
@@ -211,7 +211,13 @@ class Delivery extends BaseObject
 		return;
 	}
 
-	private static function setFailedQueue($cmd, $id)
+	/**
+	 * Increased the "failed" counter in the item delivery data
+	 *
+	 * @param string  $cmd Command
+	 * @param integer $id  Item id
+	 */
+	private static function setFailedQueue(string $cmd, int $id)
 	{
 		if (!in_array($cmd, [Delivery::POST, Delivery::POKE])) {
 			return;