diff --git a/appinfo/routes.php b/appinfo/routes.php
index 30803f9..27cdf81 100644
--- a/appinfo/routes.php
+++ b/appinfo/routes.php
@@ -23,10 +23,6 @@ return ['routes' => [
 	['name' => 'bookmark#set', 'url' => '/bookmark', 'verb' => 'POST'],
 	['name' => 'bookmark#delete', 'url' => '/bookmark/{fileId}/{name}', 'verb' => 'DELETE'],
 
-	// Metadata
-	['name' => 'metadata#get', 'url' => '/metadata/{fileId}/{name}', 'verb' => 'GET', 'defaults' => ['name' => '']],
-	['name' => 'metadata#set', 'url' => '/metadata/{fileId}/{name}/{value}', 'verb' => 'POST'],
-
 	// Preferences
 	['name' => 'preference#get_default', 'url' => '/preference/default/{scope}/{name}', 'verb' => 'GET', 'defaults' => ['name' => '']],
 	['name' => 'preference#set_default', 'url' => '/preference/default', 'verb' => 'POST'],
@@ -34,7 +30,7 @@ return ['routes' => [
 	['name' => 'preference#get', 'url' => '/preference/{fileId}/{scope}/{name}', 'verb' => 'GET', 'defaults' => ['name' => '']],
 	['name' => 'preference#set', 'url' => '/preference', 'verb' => 'POST'],
 	['name' => 'preference#delete', 'url' => '/preference/{fileId}/{scope}/{name}', 'verb' => 'DELETE'],
-	
+
 	// User Settings
 	['name' => 'settings#setPreference', 'url' => '/settings/set', 'verb' => 'POST'],
 ]];
diff --git a/lib/Controller/BookmarkController.php b/lib/Controller/BookmarkController.php
index f4a2d86..c608f10 100644
--- a/lib/Controller/BookmarkController.php
+++ b/lib/Controller/BookmarkController.php
@@ -12,23 +12,23 @@ namespace OCA\Epubreader\Controller;
 
 use OCA\Epubreader\Service\BookmarkService;
 use OCP\AppFramework\Controller;
-
-
+use OCP\AppFramework\Http\JSONResponse;
 use OCP\IRequest;
 
 class BookmarkController extends Controller {
 
-	private $bookmarkService;
+	private BookmarkService $bookmarkService;
 
 	/**
 	 * @param string $AppName
 	 * @param IRequest $request
 	 * @param BookmarkService $bookmarkService
 	 */
-	public function __construct($AppName,
+	public function __construct(
+		string $AppName,
 		IRequest $request,
-		BookmarkService $bookmarkService) {
-
+		BookmarkService $bookmarkService
+	) {
 		parent::__construct($AppName, $request);
 		$this->bookmarkService = $bookmarkService;
 	}
@@ -40,12 +40,11 @@ class BookmarkController extends Controller {
 	 * @NoCSRFRequired
 	 *
 	 * @param int $fileId
-	 * @param string $name
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
+	 * @param ?string $name
+	 * @param ?string $type
 	 */
-	public function get($fileId, $name, $type = null) {
-		return $this->bookmarkService->get($fileId, $name, $type);
+	public function get(int $fileId, ?string $name = null, ?string $type = null): JSONResponse {
+		return new JSONResponse($this->bookmarkService->get($fileId, $name, $type));
 	}
 
 	/**
@@ -57,14 +56,13 @@ class BookmarkController extends Controller {
 	 * @param int $fileId
 	 * @param string $name
 	 * @param string $value
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
+	 * @param ?string $type
+	 * @param ?string $content
 	 */
-	public function set($fileId, $name, $value, $type = null, $content = null) {
-		return $this->bookmarkService->set($fileId, $name, $value, $type, $content);
+	public function set(int $fileId, string $name, string $value, ?string $type = null, ?string $content = null): JSONResponse {
+		return new JSONResponse($this->bookmarkService->set($fileId, $name, $value, $type, $content));
 	}
 
-
 	/**
 	 * @brief return cursor for $fileId
 	 *
@@ -72,11 +70,9 @@ class BookmarkController extends Controller {
 	 * @NoCSRFRequired
 	 *
 	 * @param int $fileId
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
 	 */
-	public function getCursor($fileId) {
-		return $this->bookmarkService->getCursor($fileId);
+	public function getCursor(int $fileId): JSONResponse {
+		return new JSONResponse($this->bookmarkService->getCursor($fileId));
 	}
 
 	/**
@@ -87,11 +83,9 @@ class BookmarkController extends Controller {
 	 *
 	 * @param int $fileId
 	 * @param string $value
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
 	 */
-	public function setCursor($fileId, $value) {
-		return $this->bookmarkService->setCursor($fileId, $value);
+	public function setCursor(int $fileId, string $value): JSONResponse {
+		return new JSONResponse($this->bookmarkService->setCursor($fileId, $value));
 	}
 
 	/**
@@ -102,10 +96,9 @@ class BookmarkController extends Controller {
 	 *
 	 * @param int $fileId
 	 * @param string name
-	 *
 	 */
-	public function delete($fileId, $name) {
-		return $this->bookmarkService->delete($fileId, $name);
+	public function delete(int $fileId, string $name): void {
+		$this->bookmarkService->delete($fileId, $name);
 	}
 
 	/**
@@ -115,9 +108,8 @@ class BookmarkController extends Controller {
 	 * @NoCSRFRequired
 	 *
 	 * @param int $fileId
-	 *
 	 */
-	public function deleteCursor($fileId) {
-		return $this->bookmarkService->deleteCursor($fileId);
+	public function deleteCursor(int $fileId): void {
+		$this->bookmarkService->deleteCursor($fileId);
 	}
 }
diff --git a/lib/Controller/MetadataController.php b/lib/Controller/MetadataController.php
deleted file mode 100644
index a9b87ef..0000000
--- a/lib/Controller/MetadataController.php
+++ /dev/null
@@ -1,80 +0,0 @@
-<?php
-/**
- * @author Frank de Lange
- * @copyright 2017 Frank de Lange
- *
- * This file is licensed under the Affero General Public License version 3 or
- * later.
- * See the COPYING-README file.
- */
-
-namespace OCA\Epubreader\Controller;
-
-use OCA\Epubreader\Service\MetadataService;
-use OCP\AppFramework\Controller;
-
-use OCP\IRequest;
-
-class MetadataController extends Controller {
-
-	private $metadataService;
-
-	/**
-	 * @param string $AppName
-	 * @param IRequest $request
-	 * @param MetadataService $metadataService
-	 */
-	public function __construct($AppName,
-		IRequest $request,
-		MetadataService $metadataService) {
-
-		parent::__construct($AppName, $request);
-		$this->metadataService = $metadataService;
-	}
-
-
-	/**
-	 * @brief write metadata
-	 *
-	 * @NoAdminRequired
-	 *
-	 * @param int $fileId
-	 * @param string $value
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
-	 */
-	public function setAll($fileId, $value) {
-		return $this->metadataService->setAll($fileId, $value);
-	}
-
-	/**
-	 * @brief return metadata item
-	 *
-	 * @NoAdminRequired
-	 * @NoCSRFRequired
-	 *
-	 * @param int $fileId
-	 * @param string $name
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
-	 */
-	public function get($fileId, $name) {
-		return $this->metadataService->get($fileId, $name);
-	}
-
-	/**
-	 * @brief write metadata item
-	 *
-	 * @NoAdminRequired
-	 *
-	 * @param int $fileId
-	 * @param string $name
-	 * @param string $value
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
-	 */
-	public function set($fileId, $name, $value) {
-		return $this->metadataService->set($fileId, $name, $value);
-	}
-
-}
diff --git a/lib/Controller/PageController.php b/lib/Controller/PageController.php
index b9a8f1a..13427dd 100644
--- a/lib/Controller/PageController.php
+++ b/lib/Controller/PageController.php
@@ -11,29 +11,26 @@
 namespace OCA\Epubreader\Controller;
 
 use OCA\Epubreader\Service\BookmarkService;
-use OCA\Epubreader\Service\MetadataService;
 use OCA\Epubreader\Service\PreferenceService;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\ContentSecurityPolicy;
 use OCP\AppFramework\Http\TemplateResponse;
+use OCP\Files\FileInfo;
+use OCP\Files\Folder;
 use OCP\Files\IRootFolder;
 use OCP\Files\NotFoundException;
-
 use OCP\IRequest;
 use OCP\IURLGenerator;
 use OCP\Share\IManager;
 
 class PageController extends Controller {
 
-	/** @var IURLGenerator */
-	private $urlGenerator;
-	/** @var IRootFolder */
-	private $rootFolder;
-	private $shareManager;
-	private $userId;
-	private $bookmarkService;
-	private $metadataService;
-	private $preferenceService;
+	private IURLGenerator $urlGenerator;
+	private IRootFolder $rootFolder;
+	private IManager $shareManager;
+	private string $userId;
+	private BookmarkService $bookmarkService;
+	private PreferenceService $preferenceService;
 
 	/**
 	 * @param string $AppName
@@ -44,25 +41,23 @@ class PageController extends Controller {
 	 * @param string $UserId
 	 * @param BookmarkService $bookmarkService
 	 * @param PreferenceService $preferenceService
-	 * @param MetadataService $metadataService
 	 */
 	public function __construct(
-		$AppName,
+		string $AppName,
 		IRequest $request,
 		IURLGenerator $urlGenerator,
 		IRootFolder $rootFolder,
 		IManager $shareManager,
-		$UserId,
+		string $UserId,
 		BookmarkService $bookmarkService,
 		PreferenceService $preferenceService,
-		MetadataService $metadataService) {
+	) {
 		parent::__construct($AppName, $request);
 		$this->urlGenerator = $urlGenerator;
 		$this->rootFolder = $rootFolder;
 		$this->shareManager = $shareManager;
 		$this->userId = $UserId;
 		$this->bookmarkService = $bookmarkService;
-		$this->metadataService = $metadataService;
 		$this->preferenceService = $preferenceService;
 	}
 
@@ -72,7 +67,7 @@ class PageController extends Controller {
 	 *
 	 * @return TemplateResponse
 	 */
-	public function showReader() {
+	public function showReader(): TemplateResponse {
 		$templates = [
 			'application/epub+zip' => 'epubreader',
 			'application/x-cbr' => 'cbreader',
@@ -101,7 +96,7 @@ class PageController extends Controller {
 			'cursor' => $this->toJson($this->bookmarkService->getCursor($fileId)),
 			'defaults' => $this->toJson($this->preferenceService->getDefault($scope)),
 			'preferences' => $this->toJson($this->preferenceService->get($scope, $fileId)),
-			'metadata' => $this->toJson($this->metadataService->get($fileId)),
+			'metadata' => $this->toJson([]),
 			'annotations' => $this->toJson($this->bookmarkService->get($fileId))
 		];
 
@@ -110,7 +105,6 @@ class PageController extends Controller {
 		$policy->addAllowedStyleDomain('blob:');
 		$policy->addAllowedScriptDomain('\'self\'');
 		$policy->addAllowedFrameDomain('\'self\'');
-		$policy->addAllowedChildSrcDomain('\'self\'');
 		$policy->addAllowedFontDomain('\'self\'');
 		$policy->addAllowedFontDomain('data:');
 		$policy->addAllowedFontDomain('blob:');
@@ -132,22 +126,21 @@ class PageController extends Controller {
 	 * @return array
 	 * @throws NotFoundException
 	 */
-	private function getFileInfo($path) {
+	private function getFileInfo(string $path): array {
 		$count = 0;
 		$shareToken = preg_replace("/(?:\/index\.php)?\/s\/([A-Za-z0-9]{15,32})\/download.*/", "$1", $path, 1, $count);
 
 		if ($count === 1) {
-
 			/* shared file or directory */
 			$node = $this->shareManager->getShareByToken($shareToken)->getNode();
 			$type = $node->getType();
 
 			/* shared directory, need file path to continue, */
-			if ($type == \OCP\Files\FileInfo::TYPE_FOLDER) {
+			if ($type == FileInfo::TYPE_FOLDER && $node instanceof Folder) {
 				$query = [];
 				parse_str(parse_url($path, PHP_URL_QUERY), $query);
-				if (isset($query['path']) && isset($query['files'])) {
-					$node = $node->get($query['path'])->get($query['files']);
+				if (isset($query['path'])) {
+					$node = $node->get($query['path']);
 				} else {
 					throw new NotFoundException('Shared file path or name not set');
 				}
@@ -171,7 +164,10 @@ class PageController extends Controller {
 		];
 	}
 
-	private function toJson($value) {
+	/**
+	 * @param mixed $value
+	 */
+	private function toJson($value): string {
 		return htmlspecialchars(json_encode($value), ENT_QUOTES, 'UTF-8');
 	}
 }
diff --git a/lib/Controller/PreferenceController.php b/lib/Controller/PreferenceController.php
index ec0887e..7505aed 100644
--- a/lib/Controller/PreferenceController.php
+++ b/lib/Controller/PreferenceController.php
@@ -12,28 +12,24 @@ namespace OCA\Epubreader\Controller;
 
 use OCA\Epubreader\Service\PreferenceService;
 use OCP\AppFramework\Controller;
+use OCP\AppFramework\Http\JSONResponse;
 use OCP\IRequest;
 
-use OCP\IURLGenerator;
-
 class PreferenceController extends Controller {
 
-	private $urlGenerator;
-	private $preferenceService;
+	private PreferenceService $preferenceService;
 
 	/**
 	 * @param string $AppName
 	 * @param IRequest $request
-	 * @param IURLGenerator $urlGenerator
 	 * @param PreferenceService $preferenceService
 	 */
-	public function __construct($AppName,
+	public function __construct(
+		string $AppName,
 		IRequest $request,
-		IURLGenerator $urlGenerator,
-		PreferenceService $preferenceService) {
-
+		PreferenceService $preferenceService
+	) {
 		parent::__construct($AppName, $request);
-		$this->urlGenerator = $urlGenerator;
 		$this->preferenceService = $preferenceService;
 	}
 
@@ -45,12 +41,10 @@ class PreferenceController extends Controller {
 	 *
 	 * @param string $scope
 	 * @param int $fileId
-	 * @param string $name if null, return all preferences for $scope + $fileId
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
+	 * @param ?string $name if null, return all preferences for $scope + $fileId
 	 */
-	public function get($scope, $fileId, $name) {
-		return $this->preferenceService->get($scope, $fileId, $name);
+	public function get(string $scope, int $fileId, ?string $name = null): JSONResponse {
+		return new JSONResponse($this->preferenceService->get($scope, $fileId, $name));
 	}
 
 	/**
@@ -66,8 +60,8 @@ class PreferenceController extends Controller {
 	 *
 	 * @return array|\OCP\AppFramework\Http\JSONResponse
 	 */
-	public function set($scope, $fileId, $name, $value) {
-		return $this->preferenceService->set($scope, $fileId, $name, $value);
+	public function set(string $scope, int $fileId, string $name, string $value) {
+		return new JSONResponse($this->preferenceService->set($scope, $fileId, $name, $value));
 	}
 
 
@@ -79,11 +73,9 @@ class PreferenceController extends Controller {
 	 *
 	 * @param string $scope
 	 * @param string $name if null, return all default preferences for scope
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
 	 */
-	public function getDefault($scope, $name) {
-		return $this->preferenceService->getDefault($scope, $name);
+	public function getDefault(string $scope, string $name): JSONResponse {
+		return new JSONResponse($this->preferenceService->getDefault($scope, $name));
 	}
 
 	/**
@@ -95,11 +87,9 @@ class PreferenceController extends Controller {
 	 * @param string $scope
 	 * @param string $name
 	 * @param string $value
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
 	 */
-	public function setDefault($scope, $name, $value) {
-		return $this->preferenceService->setDefault($scope, $name, $value);
+	public function setDefault(string $scope, string $name, string $value): JSONResponse {
+		return new JSONResponse($this->preferenceService->setDefault($scope, $name, $value));
 	}
 
 	/**
@@ -108,20 +98,18 @@ class PreferenceController extends Controller {
 	 * @param string $scope
 	 * @param int $fileId
 	 * @param string $name
-	 *
 	 */
-	public function delete($scope, $fileId, $name) {
-		return $this->preferenceService->delete($scope, $fileId, $name);
+	public function delete(string $scope, int $fileId, string $name): void {
+		$this->preferenceService->delete($scope, $fileId, $name);
 	}
 
 	/**
 	 * @brief delete default preference
 	 *
-	 * @param $scope
-	 * @param $name
-	 *
+	 * @param string $scope
+	 * @param string $name
 	 */
-	public function deleteDefault($scope, $name) {
-		return $this->preferenceService->deleteDefault($scope, $name);
+	public function deleteDefault(string $scope, string $name): void {
+		$this->preferenceService->deleteDefault($scope, $name);
 	}
 }
diff --git a/lib/Controller/SettingsController.php b/lib/Controller/SettingsController.php
index aeca7a1..5e82f47 100644
--- a/lib/Controller/SettingsController.php
+++ b/lib/Controller/SettingsController.php
@@ -13,33 +13,11 @@
 namespace OCA\Epubreader\Controller;
 
 use OCA\Epubreader\Config;
-use OCA\Epubreader\Service\PreferenceService;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\JSONResponse;
-use OCP\IRequest;
-use OCP\IURLGenerator;
 
 class SettingsController extends Controller {
 
-	private $urlGenerator;
-	private $preferenceService;
-
-	/**
-	 * @param string $AppName
-	 * @param IRequest $request
-	 * @param IURLGenerator $urlGenerator
-	 * @param PreferenceService $preferenceService
-	 */
-	public function __construct($AppName,
-		IRequest $request,
-		IURLGenerator $urlGenerator,
-		PreferenceService $preferenceService) {
-
-		parent::__construct($AppName, $request);
-		$this->urlGenerator = $urlGenerator;
-		$this->preferenceService = $preferenceService;
-	}
-
 	/**
 	 * @brief set preference for file type association
 	 *
@@ -48,11 +26,8 @@ class SettingsController extends Controller {
 	 * @param int $EpubEnable
 	 * @param int $PdfEnable
 	 * @param int $CbxEnable
-	 *
-	 * @return array|\OCP\AppFramework\Http\JSONResponse
 	 */
-	public function setPreference(int $EpubEnable, int $PdfEnable, int $CbxEnable) {
-
+	public function setPreference(int $EpubEnable, int $PdfEnable, int $CbxEnable): JSONResponse {
 		$l = \OC::$server->getL10N('epubreader');
 
 		Config::set('epub_enable', $EpubEnable);
diff --git a/lib/Db/Bookmark.php b/lib/Db/Bookmark.php
index 20e3158..0c85f34 100644
--- a/lib/Db/Bookmark.php
+++ b/lib/Db/Bookmark.php
@@ -12,13 +12,12 @@ namespace OCA\Epubreader\Db;
 
 class Bookmark extends ReaderEntity implements \JsonSerializable {
 
-	protected $userId;  // user
-	protected $fileId;  // book (identified by fileId) for which this mark is valid
-	protected $type;    // type, defaults to "bookmark"
-	protected $name;    // name, defaults to $location
-	protected $value;   // bookmark value (format-specific, eg. page number for PDF, CFI for epub, etc)
-	protected $content; // bookmark content (annotations etc), can be empty
-	protected $lastModified;    // modification timestamp
+	protected string $userId; // user
+	protected int $fileId; // book (identified by fileId) for which this mark is valid
+	protected string $type; // type, defaults to "bookmark"
+	protected string $name; // name, defaults to $location
+	protected string $value; // bookmark value (format-specific, eg. page number for PDF, CFI for epub, etc)
+	protected string $content; // bookmark content (annotations etc), can be empty
 
 	public function jsonSerialize(): array {
 		return [
@@ -33,7 +32,7 @@ class Bookmark extends ReaderEntity implements \JsonSerializable {
 		];
 	}
 
-	public function toService() {
+	public function toService(): array {
 		return [
 			'name' => $this->getName(),
 			'type' => $this->getType(),
@@ -43,59 +42,51 @@ class Bookmark extends ReaderEntity implements \JsonSerializable {
 		];
 	}
 
-	public function getUserId() {
+	public function getUserId(): string {
 		return $this->userId;
 	}
 
-	public function setUserId($userId) {
+	public function setUserId(string $userId): void {
 		$this->userId = $userId;
 	}
 
-	public function getFileId() {
+	public function getFileId(): int {
 		return $this->fileId;
 	}
 
-	public function setFileId(int $fileId) {
+	public function setFileId(int $fileId): void {
 		$this->fileId = $fileId;
 	}
 
-	public function getType() {
+	public function getType(): string {
 		return $this->type;
 	}
 
-	public function setType($type) {
+	public function setType(string $type): void {
 		$this->type = $type;
 	}
 
-	public function getName() {
+	public function getName(): string {
 		return $this->name;
 	}
 
-	public function setName(string $name) {
+	public function setName(string $name): void {
 		$this->name = $name;
 	}
 
-	public function getValue() {
+	public function getValue(): string {
 		return $this->value;
 	}
 
-	public function setValue(string $value) {
+	public function setValue(string $value): void {
 		$this->value = $value;
 	}
 
-	public function getContent() {
+	public function getContent(): string {
 		return $this->content;
 	}
 
-	public function setContent($content) {
+	public function setContent(string $content): void {
 		$this->content = $content;
 	}
-
-	public function getLastModified() {
-		return $this->lastModified;
-	}
-
-	public function setLastModified($lastModified) {
-		$this->lastModified = $lastModified;
-	}
 }
diff --git a/lib/Db/BookmarkMapper.php b/lib/Db/BookmarkMapper.php
index 2578cc9..479c3a1 100644
--- a/lib/Db/BookmarkMapper.php
+++ b/lib/Db/BookmarkMapper.php
@@ -11,31 +11,31 @@
 namespace OCA\Epubreader\Db;
 
 use OCA\Epubreader\Utility\Time;
-use OCP\AppFramework\Db\Entity;
 use OCP\IDBConnection;
 
 class BookmarkMapper extends ReaderMapper {
 
-	private $userId;
+	private string $userId;
 
 	/**
 	 * @param IDbConnection $db
-	 * @param $UserId
+	 * @param string $UserId
 	 * @param Time $time
 	 */
-	public function __construct(IDBConnection $db, $UserId, Time $time) {
+	public function __construct(IDBConnection $db, string $UserId, Time $time) {
 		parent::__construct($db, 'reader_bookmarks', Bookmark::class, $time);
-		/** @var int $UserId */
 		$this->userId = $UserId;
 	}
 
 	/**
 	 * @brief get bookmarks for $fileId+$userId(+$name)
-	 * @param $fileId
-	 * @param string $name
-	 * @return array
+	 * @param int $fileId
+	 * @param ?string $name
+	 * @param ?string $type
+	 *
+	 * @return ReaderEntity[]
 	 */
-	public function get(int $fileId, $name, $type = null) {
+	public function get(int $fileId, ?string $name = null, ?string $type = null): array {
 		$query = $this->db->getQueryBuilder();
 		$query->select('*')
 			->from($this->getTableName())
@@ -57,17 +57,18 @@ class BookmarkMapper extends ReaderMapper {
 	 * @brief write bookmark to database
 	 *
 	 * @param int $fileId
-	 * @param string $name
+	 * @param ?string $name
 	 * @param string $value
+	 * @param ?string $type
+	 * @param ?string $content
 	 *
-	 * @return Entity the newly created or updated bookmark
+	 * @return ReaderEntity the newly created or updated bookmark
 	 */
-	public function set($fileId, $name, $value, $type, $content = null) {
-
+	public function set(int $fileId, ?string $name = null, string $value, ?string $type = null, ?string $content = null): ReaderEntity {
+		/** @var Bookmark[] $result */
 		$result = $this->get($fileId, $name);
 
 		if(empty($result)) {
-
 			// anonymous bookmarks are named after their contents
 			if (null === $name) {
 				$name = $value;
@@ -84,13 +85,13 @@ class BookmarkMapper extends ReaderMapper {
 			$bookmark->setType($type);
 			$bookmark->setName($name);
 			$bookmark->setValue($value);
-			$bookmark->setContent($content);
+			$bookmark->setContent($content ?? '');
 
 			$this->insert($bookmark);
 		} else {
 			$bookmark = $result[0];
 			$bookmark->setValue($value);
-			$bookmark->setContent($content);
+			$bookmark->setContent($content ?? '');
 
 			$this->update($bookmark);
 		}
diff --git a/lib/Db/Preference.php b/lib/Db/Preference.php
index b994a12..d19520c 100644
--- a/lib/Db/Preference.php
+++ b/lib/Db/Preference.php
@@ -12,12 +12,11 @@ namespace OCA\Epubreader\Db;
 
 class Preference extends ReaderEntity implements \JsonSerializable {
 
-	protected $userId;  // user for whom this preference is valid
-	protected $scope;   // scope (default or specific renderer)
-	protected $fileId;  // file for which this preference is set
-	protected $name;    // preference name
-	protected $value;   // preference value
-	protected $lastModified;    // modification timestamp
+	protected string $userId; // user for whom this preference is valid
+	protected string $scope; // scope (default or specific renderer)
+	protected int $fileId; // file for which this preference is set
+	protected string $name; // preference name
+	protected string $value; // preference value
 
 	public function jsonSerialize(): array {
 		return [
@@ -30,58 +29,50 @@ class Preference extends ReaderEntity implements \JsonSerializable {
 		];
 	}
 
-	public function toService() {
+	public function toService(): array {
 		return [
 			'name' => $this->getName(),
 			'value' => $this->conditional_json_decode($this->getValue()),
 		];
 	}
 
-	public function getUserId() {
+	public function getUserId(): string {
 		return $this->userId;
 	}
 
-	public function setUserId($userId) {
+	public function setUserId(string $userId): void {
 		$this->userId = $userId;
 	}
 
-	public function getScope() {
+	public function getScope(): string {
 		return $this->scope;
 	}
 
-	public function setScope(string $scope) {
+	public function setScope(string $scope): void {
 		$this->scope = $scope;
 	}
 
-	public function getFileId() {
+	public function getFileId(): int {
 		return $this->fileId;
 	}
 
-	public function setFileId(int $fileId) {
+	public function setFileId(int $fileId): void {
 		$this->fileId = $fileId;
 	}
 
-	public function getName() {
+	public function getName(): string {
 		return $this->name;
 	}
 
-	public function setName(string $name) {
+	public function setName(string $name): void {
 		$this->name = $name;
 	}
 
-	public function getValue() {
+	public function getValue(): string {
 		return $this->value;
 	}
 
-	public function setValue(string $value) {
+	public function setValue(string $value): void {
 		$this->value = $value;
 	}
-
-	public function getLastModified() {
-		return $this->lastModified;
-	}
-
-	public function setLastModified($lastModified) {
-		$this->lastModified = $lastModified;
-	}
 }
diff --git a/lib/Db/PreferenceMapper.php b/lib/Db/PreferenceMapper.php
index 60485eb..d213397 100644
--- a/lib/Db/PreferenceMapper.php
+++ b/lib/Db/PreferenceMapper.php
@@ -11,14 +11,13 @@
 namespace OCA\Epubreader\Db;
 
 use OCA\Epubreader\Utility\Time;
-use OCP\AppFramework\Db\Entity;
 use OCP\IDBConnection;
 
 class PreferenceMapper extends ReaderMapper {
 
-	private $userId;
+	private string $userId;
 
-	public function __construct(IDBConnection $db, $UserId, Time $time) {
+	public function __construct(IDBConnection $db, string $UserId, Time $time) {
 		parent::__construct($db, 'reader_prefs', Preference::class, $time);
 		$this->userId = $UserId;
 	}
@@ -28,10 +27,11 @@ class PreferenceMapper extends ReaderMapper {
 	 *
 	 * @param string $scope
 	 * @param int $fileId
-	 * @param string $name
-	 * @return array
+	 * @param ?string $name
+	 *
+	 * @return ReaderEntity[]
 	 */
-	public function get($scope, $fileId, $name = null) {
+	public function get(string $scope, int $fileId, ?string $name = null): array {
 		$query = $this->db->getQueryBuilder();
 		$query->select('*')
 			->from($this->getTableName())
@@ -54,14 +54,13 @@ class PreferenceMapper extends ReaderMapper {
 	 * @param string $name
 	 * @param string $value
 	 *
-	 * @return Entity the newly created or updated preference
+	 * @return ReaderEntity the newly created or updated preference
 	 */
-	public function set($scope, $fileId, $name, $value) {
-
+	public function set(string $scope, int $fileId, string $name, string $value): ReaderEntity {
+		/** @var Preference[] $result */
 		$result = $this->get($scope, $fileId, $name);
 
 		if(empty($result)) {
-
 			$preference = new Preference();
 			$preference->setScope($scope);
 			$preference->setFileId($fileId);
diff --git a/lib/Db/ReaderEntity.php b/lib/Db/ReaderEntity.php
index 80723b4..a95bc9f 100644
--- a/lib/Db/ReaderEntity.php
+++ b/lib/Db/ReaderEntity.php
@@ -12,12 +12,12 @@ namespace OCA\Epubreader\Db;
 
 use OCP\AppFramework\Db\Entity;
 
-class ReaderEntity extends Entity {
+abstract class ReaderEntity extends Entity {
 
-	private $lastModified;
+	protected int $lastModified; // modification timestamp
 
 	/* returns decoded json if input is json, otherwise returns input */
-	public static function conditional_json_decode($el) {
+	public static function conditional_json_decode(string $el): mixed {
 		$result = json_decode($el);
 		if (json_last_error() === JSON_ERROR_NONE) {
 			return $result;
@@ -26,12 +26,13 @@ class ReaderEntity extends Entity {
 		}
 	}
 
-	public function getLastModified() {
+	public function getLastModified(): int {
 		return $this->lastModified;
 	}
 
-	public function setLastModified(string $lastModified) {
+	public function setLastModified(int $lastModified): void {
 		$this->lastModified = $lastModified;
 	}
 
+	abstract public function toService(): array;
 }
diff --git a/lib/Db/ReaderMapper.php b/lib/Db/ReaderMapper.php
index da131f7..1f6af8d 100644
--- a/lib/Db/ReaderMapper.php
+++ b/lib/Db/ReaderMapper.php
@@ -13,7 +13,6 @@ namespace OCA\Epubreader\Db;
 use OCA\Epubreader\Utility\Time;
 use OCP\AppFramework\Db\Entity;
 use OCP\AppFramework\Db\QBMapper;
-
 use OCP\IDBConnection;
 
 /**
@@ -21,12 +20,15 @@ use OCP\IDBConnection;
  */
 abstract class ReaderMapper extends QBMapper {
 
-	/**
-	 * @var Time
-	 */
-	private $time;
+	private Time $time;
 
-	public function __construct(IDBConnection $db, $table, $entity, Time $time) {
+	/**
+	 * @param IDBConnection $db Instance of the Db abstraction layer
+	 * @param string $table the name of the table. set this to allow entity
+	 * @param class-string<ReaderEntity>|null $entity the name of the entity that the sql should be mapped to queries without using sql
+	 * @param Time $time
+	 */
+	public function __construct(IDBConnection $db, string $table, ?string $entity = null, Time $time) {
 		parent::__construct($db, $table, $entity);
 		$this->time = $time;
 	}
diff --git a/lib/Hooks.php b/lib/Hooks.php
index a3979d8..19bc86e 100644
--- a/lib/Hooks.php
+++ b/lib/Hooks.php
@@ -17,7 +17,7 @@ use OCP\Util;
 
 class Hooks {
 
-	public static function register() {
+	public static function register(): void {
 		Util::connectHook('\OCP\Config', 'js', 'OCA\Epubreader\Hooks', 'announce_settings');
 
 		\OC::$server->getRootFolder()->listen('\OC\Files', 'preDelete', function (Node $node) {
@@ -32,7 +32,7 @@ class Hooks {
 		});
 	}
 
-	public static function announce_settings(array $settings) {
+	public static function announce_settings(array $settings): void {
 		// Nextcloud encodes this as JSON, Owncloud does not (yet) (#75)
 		// TODO: rmeove this when Owncloud starts encoding oc_appconfig as JSON just like it already encodes most other properties
 		$isJson = self::isJson($settings['array']['oc_appconfig']);
@@ -43,27 +43,27 @@ class Hooks {
 		$settings['array']['oc_appconfig'] = ($isJson) ? json_encode($array) : $array;
 	}
 
-	protected static function deleteFile(IDBConnection $connection, $fileId) {
+	protected static function deleteFile(IDBConnection $connection, int $fileId): void {
 		$queryBuilder = $connection->getQueryBuilder();
 		$queryBuilder->delete('reader_bookmarks')->where('file_id = file_id')->setParameter('file_id', $fileId);
-		$queryBuilder->execute();
+		$queryBuilder->executeStatement();
 
 		$queryBuilder = $connection->getQueryBuilder();
 		$queryBuilder->delete('reader_prefs')->where('file_id = file_id')->setParameter('file_id', $fileId);
-		$queryBuilder->execute();
+		$queryBuilder->executeStatement();
 	}
 
-	protected static function deleteUser(IDBConnection $connection, $userId) {
+	protected static function deleteUser(IDBConnection $connection, string $userId): void {
 		$queryBuilder = $connection->getQueryBuilder();
 		$queryBuilder->delete('reader_bookmarks')->where('user_id = user_id')->setParameter('user_id', $userId);
-		$queryBuilder->execute();
+		$queryBuilder->executeStatement();
 
 		$queryBuilder = $connection->getQueryBuilder();
 		$queryBuilder->delete('reader_prefs')->where('user_id = user_id')->setParameter('user_id', $userId);
-		$queryBuilder->execute();
+		$queryBuilder->executeStatement();
 	}
 
-	private static function isJson($string) {
+	private static function isJson(mixed $string): bool {
 		return is_string($string) && is_array(json_decode($string, true)) && (json_last_error() == JSON_ERROR_NONE) ? true : false;
 	}
 }
diff --git a/lib/Migration/Version010404Date20201030180941.php b/lib/Migration/Version010404Date20201030180941.php
index 98b2c49..8b56db3 100644
--- a/lib/Migration/Version010404Date20201030180941.php
+++ b/lib/Migration/Version010404Date20201030180941.php
@@ -19,16 +19,15 @@ class Version010404Date20201030180941 extends SimpleMigrationStep {
 	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
 	 * @param array $options
 	 */
-	public function preSchemaChange(IOutput $output, Closure $schemaClosure, array $options) {
+	public function preSchemaChange(IOutput $output, Closure $schemaClosure, array $options): void {
 	}
 
 	/**
 	 * @param IOutput $output
 	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
 	 * @param array $options
-	 * @return null|ISchemaWrapper
 	 */
-	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options) {
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();
 
@@ -138,6 +137,6 @@ class Version010404Date20201030180941 extends SimpleMigrationStep {
 	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
 	 * @param array $options
 	 */
-	public function postSchemaChange(IOutput $output, Closure $schemaClosure, array $options) {
+	public function postSchemaChange(IOutput $output, Closure $schemaClosure, array $options): void {
 	}
 }
diff --git a/lib/Service/BookmarkService.php b/lib/Service/BookmarkService.php
index edb6986..19e6654 100644
--- a/lib/Service/BookmarkService.php
+++ b/lib/Service/BookmarkService.php
@@ -11,6 +11,7 @@
 namespace OCA\Epubreader\Service;
 
 use OCA\Epubreader\Db\BookmarkMapper;
+use OCA\Epubreader\Db\ReaderEntity;
 
 class BookmarkService extends Service {
 
@@ -18,13 +19,11 @@ class BookmarkService extends Service {
 	public const CURSOR = '__CURSOR__';
 	public const bookmark_type = 'bookmark';
 
-	private $bookmarkMapper;
-	private $userId;
+	private BookmarkMapper $bookmarkMapper;
 
-	public function __construct(BookmarkMapper $bookmarkMapper, $UserId) {
+	public function __construct(BookmarkMapper $bookmarkMapper) {
 		parent::__construct($bookmarkMapper);
 		$this->bookmarkMapper = $bookmarkMapper;
-		$this->userId = $UserId;
 	}
 
 	/**
@@ -33,14 +32,13 @@ class BookmarkService extends Service {
 	 * bookmark type is format-dependent, eg CFI for epub, page number for CBR/CBZ, etc
 	 *
 	 * @param int $fileId
-	 * @param string $name
-	 *
-	 * @return array
+	 * @param ?string $name
+	 * @param ?string $type
 	 */
-	public function get($fileId, $name = null, $type = null) {
+	public function get($fileId, ?string $name = null, ?string $type = null): array {
 		$result = $this->bookmarkMapper->get($fileId, $name, $type);
 		return array_map(
-			function ($entity) {
+			function (ReaderEntity $entity) {
 				return $entity->toService();
 			}, $result);
 	}
@@ -51,12 +49,12 @@ class BookmarkService extends Service {
 	 * position type is format-dependent, eg CFI for epub, page number for CBR/CBZ, etc
 	 *
 	 * @param int $fileId
-	 * @param string $name
+	 * @param ?string $name
 	 * @param string $value
-	 *
-	 * @return array
+	 * @param ?string $type
+	 * @param ?string $content
 	 */
-	public function set($fileId, $name, $value, $type = null, $content = null) {
+	public function set(int $fileId, ?string $name = null, string $value, ?string $type = null, ?string $content = null): ReaderEntity {
 		return $this->bookmarkMapper->set($fileId, $name, $value, $type, $content);
 	}
 
@@ -64,14 +62,13 @@ class BookmarkService extends Service {
 	 * @brief get cursor (current position in book)
 	 *
 	 * @param int $fileId
-	 *
-	 * @return array
 	 */
-	public function getCursor($fileId) {
+	public function getCursor(int $fileId): array {
 		$result = $this->get($fileId, static::CURSOR);
 		if (count($result) === 1) {
 			return $result[0];
 		}
+		return [];
 	}
 
 	/**
@@ -79,10 +76,8 @@ class BookmarkService extends Service {
 	 *
 	 * @param int $fileId
 	 * @param string $value
-	 *
-	 * @return array
 	 */
-	public function setCursor($fileId, $value) {
+	public function setCursor(int $fileId, string $value): ReaderEntity {
 		return $this->bookmarkMapper->set($fileId, static::CURSOR, $value, static::bookmark_type);
 	}
 
@@ -90,10 +85,10 @@ class BookmarkService extends Service {
 	 * @brief delete bookmark
 	 *
 	 * @param int $fileId
-	 * @param string $name
-	 *
+	 * @param ?string $name
+	 * @param ?string $type
 	 */
-	public function delete($fileId, $name, $type = null) {
+	public function delete($fileId, ?string $name = null, ?string $type = null): void {
 		foreach ($this->bookmarkMapper->get($fileId, $name, $type) as $bookmark) {
 			$this->bookmarkMapper->delete($bookmark);
 		}
@@ -103,9 +98,8 @@ class BookmarkService extends Service {
 	 * @brief delete cursor
 	 *
 	 * @param int $fileId
-	 *
 	 */
-	public function deleteCursor($fileId) {
+	public function deleteCursor(int $fileId): void {
 		$this->delete($fileId, static::CURSOR, static::bookmark_type);
 	}
 }
diff --git a/lib/Service/MetadataService.php b/lib/Service/MetadataService.php
deleted file mode 100644
index f7981a9..0000000
--- a/lib/Service/MetadataService.php
+++ /dev/null
@@ -1,64 +0,0 @@
-<?php
-/**
- * @author Frank de Lange
- * @copyright 2017 Frank de Lange
- *
- * This file is licensed under the Affero General Public License version 3 or
- * later.
- * See the COPYING-README file.
- */
-
-namespace OCA\Epubreader\Service;
-
-use OCP\App\IAppManager;
-
-class MetadataService {
-
-	private $appManager;
-
-	/**
-	 * @param IAppManager $appManager
-	 */
-	public function __construct(IAppManager $appManager) {
-		$this->appManager = $appManager;
-	}
-
-	/**
-	 * @brief get metadata item(s)
-	 *
-	 * @param int $fileId
-	 * @param string $name
-	 *
-	 * @return array
-	 */
-	public function get($fileId, $name = null) {
-		return [];
-	}
-
-	/**
-	 * @brief write metadata to database
-	 *
-	 * @param int $fileId
-	 * @param array $value
-	 *
-	 * @return array
-	 */
-	public function setAll($fileId, $value) {
-		// no-op for now
-		return [];
-	}
-
-	/**
-	 * @brief write metadata item to database
-	 *
-	 * @param int $fileId
-	 * @param string $name
-	 * @param array $value
-	 *
-	 * @return array
-	 */
-	public function set($fileId, $name, $value) {
-		// no-op for now
-		return [];
-	}
-}
diff --git a/lib/Service/PreferenceService.php b/lib/Service/PreferenceService.php
index 4e70e7d..e3133d1 100644
--- a/lib/Service/PreferenceService.php
+++ b/lib/Service/PreferenceService.php
@@ -11,6 +11,7 @@
 namespace OCA\Epubreader\Service;
 
 use OCA\Epubreader\Db\PreferenceMapper;
+use OCA\Epubreader\Db\ReaderEntity;
 
 class PreferenceService extends Service {
 
@@ -18,7 +19,7 @@ class PreferenceService extends Service {
 	// value 0 to indicate a default preference
 	public const DEFAULTS = 0;
 
-	private $preferenceMapper;
+	private PreferenceMapper $preferenceMapper;
 
 	/**
 	 * @param PreferenceMapper $preferenceMapper
@@ -36,11 +37,11 @@ class PreferenceService extends Service {
 	 *
 	 * @param string $scope
 	 * @param int $fileId
-	 * @param string $name
+	 * @param ?string $name
 	 *
 	 * @return array
 	 */
-	public function get($scope, $fileId, $name = null) {
+	public function get(string $scope, int $fileId, ?string $name = null): array {
 		$result = $this->preferenceMapper->get($scope, $fileId, $name);
 		return array_map(
 			function ($entity) {
@@ -58,10 +59,8 @@ class PreferenceService extends Service {
 	 * @param int $fileId
 	 * @param string $name
 	 * @param string $value
-	 *
-	 * @return array
 	 */
-	public function set($scope, $fileId, $name, $value) {
+	public function set(string $scope, int $fileId, string $name, string $value): ReaderEntity {
 		return $this->preferenceMapper->set($scope, $fileId, $name, $value);
 	}
 
@@ -69,11 +68,9 @@ class PreferenceService extends Service {
 	 * @brief get default preference
 	 *
 	 * @param string $scope
-	 * @param string $name
-	 *
-	 * @return array
+	 * @param ?string $name
 	 */
-	public function getDefault($scope, $name = null) {
+	public function getDefault(string $scope, ?string $name = null): array {
 		return $this->get($scope, static::DEFAULTS, $name);
 	}
 
@@ -83,10 +80,8 @@ class PreferenceService extends Service {
 	 * @param string $scope
 	 * @param string $name
 	 * @param string $value
-	 *
-	 * @return array
 	 */
-	public function setDefault($scope, $name, $value) {
+	public function setDefault($scope, $name, $value): ReaderEntity {
 		return $this->preferenceMapper->set($scope, static::DEFAULTS, $name, $value);
 	}
 
@@ -95,10 +90,10 @@ class PreferenceService extends Service {
 	 *
 	 * @param string $scope
 	 * @param int $fileId
-	 * @param string $name
+	 * @param ?string $name
 	 *
 	 */
-	public function delete($scope, $fileId, $name) {
+	public function delete(string $scope, int $fileId, ?string $name = null): void {
 		foreach($this->preferenceMapper->get($scope, $fileId, $name) as $preference) {
 			$this->preferenceMapper->delete($preference);
 		}
@@ -108,10 +103,10 @@ class PreferenceService extends Service {
 	 * @brief delete default
 	 *
 	 * @param string $scope
-	 * @param string $name
+	 * @param ?string $name
 	 *
 	 */
-	public function deleteDefault($scope, $name) {
+	public function deleteDefault(string $scope, ?string $name = null): void {
 		$this->delete($scope, static::DEFAULTS, $name);
 	}
 }
diff --git a/lib/Service/Service.php b/lib/Service/Service.php
index 1d49070..2b861e1 100644
--- a/lib/Service/Service.php
+++ b/lib/Service/Service.php
@@ -13,8 +13,7 @@ namespace OCA\Epubreader\Service;
 use OCA\Epubreader\Db\ReaderMapper;
 
 abstract class Service {
-
-	protected $mapper;
+	protected ReaderMapper $mapper;
 
 	public function __construct(ReaderMapper $mapper) {
 		$this->mapper = $mapper;
diff --git a/lib/Settings/Personal.php b/lib/Settings/Personal.php
index eeb2ad8..0a582b3 100644
--- a/lib/Settings/Personal.php
+++ b/lib/Settings/Personal.php
@@ -17,11 +17,11 @@ use OCP\Settings\ISettings;
 
 class Personal implements ISettings {
 
-	private $userId;
-	private $configManager;
+	private string $userId;
+	private IConfig $configManager;
 
 	public function __construct(
-		$userId,
+		string $userId,
 		IConfig $configManager
 	) {
 		$this->userId = $userId;
@@ -32,13 +32,13 @@ class Personal implements ISettings {
 	 * @return TemplateResponse returns the instance with all parameters set, ready to be rendered
 	 * @since 9.1
 	 */
-	public function getForm() {
-
+	public function getForm(): TemplateResponse {
 		$parameters = [
 			'EpubEnable' => $this->configManager->getUserValue($this->userId, 'epubreader', 'epub_enable'),
 			'PdfEnable' => $this->configManager->getUserValue($this->userId, 'epubreader', 'pdf_enable'),
 			'CbxEnable' => $this->configManager->getUserValue($this->userId, 'epubreader', 'cbx_enable'),
 		];
+
 		return new TemplateResponse('epubreader', 'settings-personal', $parameters, '');
 	}
 
@@ -47,7 +47,7 @@ class Personal implements ISettings {
 	 *
 	 * @return TemplateResponse
 	 */
-	public function getPanel() {
+	public function getPanel(): TemplateResponse {
 		return $this->getForm();
 	}
 
@@ -55,7 +55,7 @@ class Personal implements ISettings {
 	 * @return string the section ID, e.g. 'sharing'
 	 * @since 9.1
 	 */
-	public function getSection() {
+	public function getSection(): string {
 		return 'epubreader';
 	}
 
@@ -64,7 +64,7 @@ class Personal implements ISettings {
 	 *
 	 * @return string
 	 */
-	public function getSectionID() {
+	public function getSectionID(): string {
 		return 'epubreader';
 	}
 
@@ -76,7 +76,7 @@ class Personal implements ISettings {
 	 * E.g.: 70
 	 * @since 9.1
 	 */
-	public function getPriority() {
+	public function getPriority(): int {
 		return 10;
 	}
 }
diff --git a/lib/Settings/PersonalSection.php b/lib/Settings/PersonalSection.php
index 2b25063..014c3b9 100644
--- a/lib/Settings/PersonalSection.php
+++ b/lib/Settings/PersonalSection.php
@@ -16,10 +16,9 @@ use OCP\IURLGenerator;
 use OCP\Settings\IIconSection;
 
 class PersonalSection implements IIconSection {
-	/** @var IURLGenerator */
-	private $urlGenerator;
-	/** @var IL10N */
-	private $l;
+
+	private IURLGenerator $urlGenerator;
+	private IL10N $l;
 
 	public function __construct(IURLGenerator $urlGenerator, IL10N $l) {
 		$this->urlGenerator = $urlGenerator;
@@ -29,18 +28,18 @@ class PersonalSection implements IIconSection {
 	/**
 	 * returns the relative path to an 16*16 icon describing the section.
 	 *
-	 * @returns string
+	 * @return string
 	 */
-	public function getIcon() {
+	public function getIcon(): string {
 		return $this->urlGenerator->imagePath('epubreader', 'app.svg');
 	}
 
 	/**
 	 * returns the ID of the section. It is supposed to be a lower case string,
 	 *
-	 * @returns string
+	 * @return string
 	 */
-	public function getID() {
+	public function getID(): string {
 		return 'epubreader';
 	}
 
@@ -49,7 +48,7 @@ class PersonalSection implements IIconSection {
 	 *
 	 * @return string
 	 */
-	public function getName() {
+	public function getName(): string {
 		return $this->l->t('EPUB/CBZ/PDF ebook reader');
 	}
 
@@ -58,7 +57,7 @@ class PersonalSection implements IIconSection {
 	 *
 	 * @return int
 	 */
-	public function getPriority() {
+	public function getPriority(): int {
 		return 20;
 	}
 }
diff --git a/lib/Utility/Time.php b/lib/Utility/Time.php
index 71c3e17..b4cbf7f 100644
--- a/lib/Utility/Time.php
+++ b/lib/Utility/Time.php
@@ -11,16 +11,16 @@
 namespace OCA\Epubreader\Utility;
 
 class Time {
-	public function getTime() {
+
+	public function getTime(): int {
 		return time();
 	}
 
 	/**
-	 * @return string the current unix time in miliseconds
+	 * @return int the current unix time in miliseconds
 	 */
-	public function getMicroTime(): string {
+	public function getMicroTime(): int {
 		list($millisecs, $secs) = explode(" ", microtime());
-		return $secs . substr($millisecs, 2, 6);
+		return (int) ($secs . substr($millisecs, 2, 6));
 	}
-
 }
diff --git a/lib/config.php b/lib/config.php
index 7cccf6a..5d88bce 100644
--- a/lib/config.php
+++ b/lib/config.php
@@ -16,6 +16,7 @@ namespace OCA\Epubreader;
  * Config class for Reader
  */
 class Config {
+
 	/**
 	 * @brief get user config value
 	 *
@@ -23,7 +24,7 @@ class Config {
 	 * @param string $default default value to use
 	 * @return string retrieved value or default
 	 */
-	public static function get($key, $default) {
+	public static function get(string $key, string $default): string {
 		return \OC::$server->getConfig()->getUserValue(\OC_User::getUser(), 'epubreader', $key, $default);
 	}
 
@@ -34,7 +35,7 @@ class Config {
 	 * @param string $value value to use
 	 * @return bool success
 	 */
-	public static function set($key, $value) {
+	public static function set(string $key, string $value): bool {
 		return \OC::$server->getConfig()->setUserValue(\OC_User::getUser(), 'epubreader', $key, $value);
 	}
 
@@ -45,7 +46,7 @@ class Config {
 	 * @param string $default default value to use
 	 * @return string retrieved value or default
 	 */
-	public static function getApp($key, $default) {
+	public static function getApp(string $key, string $default): string {
 		return \OC::$server->getConfig()->getAppValue('epubreader', $key, $default);
 	}
 
@@ -56,7 +57,7 @@ class Config {
 	 * @param string $value value to use
 	 * @return bool success
 	 */
-	public static function setApp($key, $value) {
+	public static function setApp(string $key, string $value): bool {
 		return \OC::$server->getConfig()->setAppValue('epubreader', $key, $value);
 	}
 }
diff --git a/psalm.xml b/psalm.xml
index f8ce4f9..c79ee1e 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -34,5 +34,11 @@
                 <referencedClass name="OC" />
             </errorLevel>
         </UndefinedClass>
+        <DeprecatedMethod>
+            <errorLevel type="info">
+                <referencedMethod name="OCP\Util::connectHook" />
+            </errorLevel>
+        </DeprecatedMethod>
+        <PropertyNotSetInConstructor errorLevel="suppress" />
     </issueHandlers>
 </psalm>