diff --git a/src/Model/Post.php b/src/Model/Post.php
index 93a990a37..56898e3b2 100644
--- a/src/Model/Post.php
+++ b/src/Model/Post.php
@@ -39,7 +39,7 @@ class Post
 	 * @return int    ID of inserted post
 	 * @throws \Exception
 	 */
-	public static function insert(int $uri_id, array $data = [])
+	public static function insert(int $uri_id, array $data = []): int
 	{
 		if (empty($uri_id)) {
 			throw new BadMethodCallException('Empty URI_id');
@@ -107,8 +107,10 @@ class Post
 	 * @param object $stmt statement object
 	 * @param bool   $do_close
 	 * @return array Data array
+	 * @todo Find proper type-hint for $stmt and maybe avoid boolean
 	 */
-	public static function toArray($stmt, $do_close = true) {
+	public static function toArray($stmt, bool $do_close = true)
+	{
 		if (is_bool($stmt)) {
 			return $stmt;
 		}
@@ -131,7 +133,8 @@ class Post
 	 * @return boolean Are there rows for that condition?
 	 * @throws \Exception
 	 */
-	public static function exists($condition) {
+	public static function exists(array $condition): bool
+	{
 		return DBA::exists('post-user-view', $condition);
 	}
 
@@ -151,7 +154,7 @@ class Post
 	 * $count = Post::count($condition);
 	 * @throws \Exception
 	 */
-	public static function count(array $condition = [], array $params = [])
+	public static function count(array $condition = [], array $params = []): int
 	{
 		return DBA::count('post-user-view', $condition, $params);
 	}
@@ -172,7 +175,7 @@ class Post
 	 * $count = Post::count($condition);
 	 * @throws \Exception
 	 */
-	public static function countThread(array $condition = [], array $params = [])
+	public static function countThread(array $condition = [], array $params = []): int
 	{
 		return DBA::count('post-thread-user-view', $condition, $params);
 	}
@@ -193,7 +196,7 @@ class Post
 	 * $count = Post::count($condition);
 	 * @throws \Exception
 	 */
-	public static function countPosts(array $condition = [], array $params = [])
+	public static function countPosts(array $condition = [], array $params = []): int
 	{
 		return DBA::count('post-view', $condition, $params);
 	}
@@ -209,7 +212,7 @@ class Post
 	 * @throws \Exception
 	 * @see   DBA::select
 	 */
-	public static function selectFirst(array $fields = [], array $condition = [], $params = [])
+	public static function selectFirst(array $fields = [], array $condition = [], array $params = [])
 	{
 		$params['limit'] = 1;
 
@@ -234,7 +237,7 @@ class Post
 	 * @throws \Exception
 	 * @see   DBA::select
 	 */
-	public static function selectFirstPost(array $fields = [], array $condition = [], $params = [])
+	public static function selectFirstPost(array $fields = [], array $condition = [], array $params = [])
 	{
 		$params['limit'] = 1;
 
@@ -259,7 +262,7 @@ class Post
 	 * @throws \Exception
 	 * @see   DBA::select
 	 */
-	public static function selectFirstThread(array $fields = [], array $condition = [], $params = [])
+	public static function selectFirstThread(array $fields = [], array $condition = [], array $params = [])
 	{
 		$params['limit'] = 1;
 
@@ -284,7 +287,7 @@ class Post
 	 * @return array
 	 * @throws \Exception
 	 */
-	public static function selectToArray(array $fields = [], array $condition = [], $params = [])
+	public static function selectToArray(array $fields = [], array $condition = [], array $params = [])
 	{
 		$result = self::select($fields, $condition, $params);
 
@@ -312,7 +315,7 @@ class Post
 	 * @return boolean|object
 	 * @throws \Exception
 	 */
-	private static function selectView(string $view, array $selected = [], array $condition = [], $params = [])
+	private static function selectView(string $view, array $selected = [], array $condition = [], array $params = [])
 	{
 		if (empty($selected)) {
 			$selected = array_merge(Item::DISPLAY_FIELDLIST, Item::ITEM_FIELDLIST);
@@ -337,7 +340,7 @@ class Post
 	 * @return boolean|object
 	 * @throws \Exception
 	 */
-	public static function select(array $selected = [], array $condition = [], $params = [])
+	public static function select(array $selected = [], array $condition = [], array $params = [])
 	{
 		return self::selectView('post-user-view', $selected, $condition, $params);
 	}
@@ -352,7 +355,7 @@ class Post
 	 * @return boolean|object
 	 * @throws \Exception
 	 */
-	public static function selectPosts(array $selected = [], array $condition = [], $params = [])
+	public static function selectPosts(array $selected = [], array $condition = [], array $params = [])
 	{
 		return self::selectView('post-view', $selected, $condition, $params);
 	}
@@ -367,7 +370,7 @@ class Post
 	 * @return boolean|object
 	 * @throws \Exception
 	 */
-	public static function selectThread(array $selected = [], array $condition = [], $params = [])
+	public static function selectThread(array $selected = [], array $condition = [], array $params = [])
 	{
 		return self::selectView('post-thread-user-view', $selected, $condition, $params);
 	}
@@ -384,7 +387,7 @@ class Post
 	 * @return boolean|object
 	 * @throws \Exception
 	 */
-	private static function selectViewForUser(string $view, $uid, array $selected = [], array $condition = [], $params = [])
+	private static function selectViewForUser(string $view, int $uid, array $selected = [], array $condition = [], array $params = [])
 	{
 		if (empty($selected)) {
 			$selected = Item::DISPLAY_FIELDLIST;
@@ -425,7 +428,7 @@ class Post
 	 * @return boolean|object
 	 * @throws \Exception
 	 */
-	public static function selectForUser($uid, array $selected = [], array $condition = [], $params = [])
+	public static function selectForUser(int $uid, array $selected = [], array $condition = [], array $params = [])
 	{
 		return self::selectViewForUser('post-user-view', $uid, $selected, $condition, $params);
 	}
@@ -441,7 +444,7 @@ class Post
 	 * @return boolean|object
 	 * @throws \Exception
 	 */
-	public static function selectPostsForUser($uid, array $selected = [], array $condition = [], $params = [])
+	public static function selectPostsForUser(int $uid, array $selected = [], array $condition = [], array $params = [])
 	{
 		return self::selectViewForUser('post-view', $uid, $selected, $condition, $params);
 	}
@@ -457,7 +460,7 @@ class Post
 	 * @return boolean|object
 	 * @throws \Exception
 	 */
-	public static function selectThreadForUser($uid, array $selected = [], array $condition = [], $params = [])
+	public static function selectThreadForUser(int $uid, array $selected = [], array $condition = [], array $params = [])
 	{
 		return self::selectViewForUser('post-thread-user-view', $uid, $selected, $condition, $params);
 	}
@@ -473,7 +476,7 @@ class Post
 	 * @throws \Exception
 	 * @see   DBA::select
 	 */
-	public static function selectFirstForUser($uid, array $selected = [], array $condition = [], $params = [])
+	public static function selectFirstForUser(int $uid, array $selected = [], array $condition = [], array $params = [])
 	{
 		$params['limit'] = 1;
 
@@ -640,7 +643,7 @@ class Post
 	 * @return boolean was the delete successful?
 	 * @throws \Exception
 	 */
-	public static function delete(array $conditions, array $options = [])
+	public static function delete(array $conditions, array $options = []): bool
 	{
 		return DBA::delete('post', $conditions, $options);
 	}
diff --git a/src/Model/Profile.php b/src/Model/Profile.php
index 7a6572770..8a9333734 100644
--- a/src/Model/Profile.php
+++ b/src/Model/Profile.php
@@ -54,10 +54,10 @@ class Profile
 	 *
 	 * @param integer User ID
 	 *
-	 * @return array Profile data
+	 * @return array|bool Profile data or false on error
 	 * @throws \Exception
 	 */
-	public static function getByUID($uid)
+	public static function getByUID(int $uid)
 	{
 		return DBA::selectFirst('profile', [], ['uid' => $uid]);
 	}
@@ -69,7 +69,7 @@ class Profile
 	 * @param int $id The contact owner ID
 	 * @param array $fields The selected fields
 	 *
-	 * @return array Profile data for the ID
+	 * @return array|bool Profile data for the ID or false on error
 	 * @throws \Exception
 	 */
 	public static function getById(int $uid, int $id, array $fields = [])
@@ -81,7 +81,7 @@ class Profile
 	 * Returns profile data for the contact owner
 	 *
 	 * @param int $uid The User ID
-	 * @param array $fields The fields to retrieve
+	 * @param array|bool $fields The fields to retrieve or false on error
 	 *
 	 * @return array Array of profile data
 	 * @throws \Exception
@@ -94,9 +94,9 @@ class Profile
 	/**
 	 * Update a profile entry and distribute the changes if needed
 	 *
-	 * @param array $fields
-	 * @param integer $uid
-	 * @return boolean
+	 * @param array $fields Profile fields to update
+	 * @param integer $uid User id
+	 * @return boolean Whether update was successful
 	 */
 	public static function update(array $fields, int $uid): bool
 	{
@@ -136,8 +136,10 @@ class Profile
 
 	/**
 	 * Publish a changed profile
-	 * @param int  $uid
+	 *
+	 * @param int  $uid User id
 	 * @param bool $force Force publishing to the directory
+	 * @return void
 	 */
 	public static function publishUpdate(int $uid, bool $force = false)
 	{
@@ -163,7 +165,7 @@ class Profile
 	 *
 	 * @return string Location string
 	 */
-	public static function formatLocation(array $profile)
+	public static function formatLocation(array $profile): string
 	{
 		$location = '';
 
diff --git a/src/Model/PushSubscriber.php b/src/Model/PushSubscriber.php
index 51d48d9b2..8aa67eee5 100644
--- a/src/Model/PushSubscriber.php
+++ b/src/Model/PushSubscriber.php
@@ -34,9 +34,10 @@ class PushSubscriber
 	 *
 	 * @param integer $uid User ID
 	 * @param int     $default_priority
+	 * @return void
 	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 	 */
-	public static function publishFeed($uid, $default_priority = PRIORITY_HIGH)
+	public static function publishFeed(int $uid, int $default_priority = PRIORITY_HIGH)
 	{
 		$condition = ['push' => 0, 'uid' => $uid];
 		DBA::update('push_subscriber', ['push' => 1, 'next_try' => DBA::NULL_DATETIME], $condition);
@@ -48,9 +49,10 @@ class PushSubscriber
 	 * start workers to transmit the feed data
 	 *
 	 * @param int $default_priority
+	 * @return void
 	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 	 */
-	public static function requeue($default_priority = PRIORITY_HIGH)
+	public static function requeue(int $default_priority = PRIORITY_HIGH)
 	{
 		// We'll push to each subscriber that has push > 0,
 		// i.e. there has been an update (set in notifier.php).
@@ -80,9 +82,10 @@ class PushSubscriber
 	 * @param string  $hub_callback Callback address
 	 * @param string  $hub_topic    Feed topic
 	 * @param string  $hub_secret   Subscription secret
+	 * @return void
 	 * @throws \Exception
 	 */
-	public static function renew($uid, $nick, $subscribe, $hub_callback, $hub_topic, $hub_secret)
+	public static function renew(int $uid, string $nick, int $subscribe, string $hub_callback, string $hub_topic, string $hub_secret)
 	{
 		// fetch the old subscription if it exists
 		$subscriber = DBA::selectFirst('push_subscriber', ['last_update', 'push'], ['callback_url' => $hub_callback]);
@@ -119,9 +122,10 @@ class PushSubscriber
 	 * Delay the push subscriber
 	 *
 	 * @param integer $id Subscriber ID
+	 * @return void
 	 * @throws \Exception
 	 */
-	public static function delay($id)
+	public static function delay(int $id)
 	{
 		$subscriber = DBA::selectFirst('push_subscriber', ['push', 'callback_url', 'renewed', 'nickname'], ['id' => $id]);
 		if (!DBA::isResult($subscriber)) {
@@ -158,9 +162,10 @@ class PushSubscriber
 	 *
 	 * @param integer $id          Subscriber ID
 	 * @param string  $last_update Date of last transmitted item
+	 * @return void
 	 * @throws \Exception
 	 */
-	public static function reset($id, $last_update)
+	public static function reset(int $id, string $last_update)
 	{
 		$subscriber = DBA::selectFirst('push_subscriber', ['callback_url', 'nickname'], ['id' => $id]);
 		if (!DBA::isResult($subscriber)) {