diff --git a/lib/Activity/Provider.php b/lib/Activity/Provider.php
index 18f49fcf..71cd4c30 100644
--- a/lib/Activity/Provider.php
+++ b/lib/Activity/Provider.php
@@ -54,7 +54,7 @@ class Provider implements IProvider {
 	/**
 	 * @inheritDoc
 	 */
-	public function parse($language, IEvent $event, IEvent $previousEvent = null) {
+	public function parse($language, IEvent $event, ?IEvent $previousEvent = null) {
 		if ($event->getApp() !== 'bookmarks') {
 			throw new InvalidArgumentException();
 		}
diff --git a/lib/Db/TreeMapper.php b/lib/Db/TreeMapper.php
index f32923fc..6fa789a6 100644
--- a/lib/Db/TreeMapper.php
+++ b/lib/Db/TreeMapper.php
@@ -178,7 +178,7 @@ class TreeMapper extends QBMapper {
 	 * @param IQueryBuilder|null $queryBuilder
 	 * @return IQueryBuilder
 	 */
-	protected function selectFromType(string $type, array $cols = [], IQueryBuilder $queryBuilder = null): IQueryBuilder {
+	protected function selectFromType(string $type, array $cols = [], ?IQueryBuilder $queryBuilder = null): IQueryBuilder {
 		$qb = $queryBuilder ?? $this->db->getQueryBuilder();
 		$qb->resetQueryPart('from');
 		$qb
@@ -318,7 +318,7 @@ class TreeMapper extends QBMapper {
 			$ancestors = array_flatten(array_map(function (Entity $ancestor) {
 				return $this->findParentsOf(self::TYPE_FOLDER, $ancestor->getId());
 			}, $ancestors));
-			if (0 === count($ancestors)) {
+			if (count($ancestors) === 0) {
 				return false;
 			}
 		}
@@ -336,7 +336,7 @@ class TreeMapper extends QBMapper {
 	 * @throws MultipleObjectsReturnedException
 	 * @throws UnsupportedOperation
 	 */
-	public function deleteEntry(string $type, int $id, int $folderId = null): void {
+	public function deleteEntry(string $type, int $id, ?int $folderId = null): void {
 		$this->eventDispatcher->dispatch(BeforeDeleteEvent::class, new BeforeDeleteEvent($type, $id));
 
 		if ($type === self::TYPE_FOLDER) {
@@ -439,7 +439,7 @@ class TreeMapper extends QBMapper {
 	 * @throws MultipleObjectsReturnedException
 	 * @throws UnsupportedOperation
 	 */
-	public function move(string $type, int $itemId, int $newParentFolderId, int $index = null): void {
+	public function move(string $type, int $itemId, int $newParentFolderId, ?int $index = null): void {
 		if ($type === self::TYPE_BOOKMARK) {
 			throw new UnsupportedOperation('Cannot move Bookmark');
 		}
@@ -515,7 +515,7 @@ class TreeMapper extends QBMapper {
 		if ($type !== self::TYPE_BOOKMARK) {
 			throw new UnsupportedOperation('Only bookmarks can be in multiple folders');
 		}
-		if (0 === count($folders)) {
+		if (count($folders) === 0) {
 			return;
 		}
 
@@ -537,7 +537,7 @@ class TreeMapper extends QBMapper {
 	 * @param int|null $index
 	 * @throws UnsupportedOperation|Exception
 	 */
-	public function addToFolders(string $type, int $itemId, array $folders, int $index = null): void {
+	public function addToFolders(string $type, int $itemId, array $folders, ?int $index = null): void {
 		if ($type !== self::TYPE_BOOKMARK) {
 			throw new UnsupportedOperation('Only bookmarks can be in multiple folders');
 		}
diff --git a/lib/Events/MoveEvent.php b/lib/Events/MoveEvent.php
index 8b20bf79..3eb37fa0 100644
--- a/lib/Events/MoveEvent.php
+++ b/lib/Events/MoveEvent.php
@@ -19,7 +19,7 @@ class MoveEvent extends ChangeEvent {
 	 * @param int|null $oldParent
 	 * @param int|null $newParent
 	 */
-	public function __construct(string $type, int $id, int $oldParent = null, int $newParent = null) {
+	public function __construct(string $type, int $id, ?int $oldParent = null, ?int $newParent = null) {
 		parent::__construct($type, $id);
 		$this->oldParent = $oldParent;
 		$this->newParent = $newParent;
diff --git a/lib/Middleware/ExceptionMiddleware.php b/lib/Middleware/ExceptionMiddleware.php
index b1de343e..c96f8cd6 100644
--- a/lib/Middleware/ExceptionMiddleware.php
+++ b/lib/Middleware/ExceptionMiddleware.php
@@ -7,7 +7,6 @@
 
 namespace OCA\Bookmarks\Middleware;
 
-use \OCP\AppFramework\Middleware;
 use OCA\Bookmarks\Controller\BookmarkController;
 use OCA\Bookmarks\Controller\FoldersController;
 use OCA\Bookmarks\Controller\InternalBookmarkController;
@@ -15,6 +14,7 @@ use OCA\Bookmarks\Controller\InternalFoldersController;
 use OCA\Bookmarks\Exception\UnauthenticatedError;
 use OCP\AppFramework\Http;
 use OCP\AppFramework\Http\DataResponse;
+use OCP\AppFramework\Middleware;
 
 class ExceptionMiddleware extends Middleware {
 	public function afterException($controller, $methodName, \Exception $exception): DataResponse {
diff --git a/lib/QueryParameters.php b/lib/QueryParameters.php
index f12e87cc..80fbca79 100644
--- a/lib/QueryParameters.php
+++ b/lib/QueryParameters.php
@@ -100,7 +100,7 @@ class QueryParameters {
 	 * @param array|null $columns
 	 * @return string|null
 	 */
-	public function getSortBy(string $default = null, array $columns = null): ?string {
+	public function getSortBy(?string $default = null, ?array $columns = null): ?string {
 		if (isset($default) && !isset($this->sortBy)) {
 			return $default;
 		}
diff --git a/lib/Service/Authorizer.php b/lib/Service/Authorizer.php
index 0178e189..7a2aa266 100644
--- a/lib/Service/Authorizer.php
+++ b/lib/Service/Authorizer.php
@@ -78,7 +78,7 @@ class Authorizer {
 				$this->setUserId($this->userSession->getUser()->getUID());
 				return;
 			}
-			if (false === $this->userSession->login($request->server['PHP_AUTH_USER'], $request->server['PHP_AUTH_PW'])) {
+			if ($this->userSession->login($request->server['PHP_AUTH_USER'], $request->server['PHP_AUTH_PW']) === false) {
 				return;
 			}
 			$this->setUserId($this->userSession->getUser()->getUID());
@@ -90,7 +90,7 @@ class Authorizer {
 					return;
 				}
 				[$username, $password] = explode(':', base64_decode($credentials));
-				if (false === $this->userSession->login($username, $password)) {
+				if ($this->userSession->login($username, $password) === false) {
 					return;
 				}
 				$this->setUserId($this->userSession->getUser()->getUID());
diff --git a/lib/Service/BookmarkService.php b/lib/Service/BookmarkService.php
index 50463c1e..7c7e7862 100644
--- a/lib/Service/BookmarkService.php
+++ b/lib/Service/BookmarkService.php
@@ -131,7 +131,7 @@ class BookmarkService {
 	 * @throws UrlParseError
 	 * @throws UserLimitExceededError
 	 */
-	public function create(string $userId, string $url = '', string $title = null, string $description = null, array $tags = null, $folders = []): Bookmark {
+	public function create(string $userId, string $url = '', ?string $title = null, ?string $description = null, ?array $tags = null, $folders = []): Bookmark {
 		$bookmark = null;
 		$ownFolders = array_filter($folders, function ($folderId) use ($userId) {
 			/**
@@ -174,7 +174,7 @@ class BookmarkService {
 	 * @throws UserLimitExceededError
 	 * @throws UnsupportedOperation
 	 */
-	private function _addBookmark($userId, $url, string $title = null, $description = null, array $tags = null, array $folders = []): Bookmark {
+	private function _addBookmark($userId, $url, ?string $title = null, $description = null, ?array $tags = null, array $folders = []): Bookmark {
 		$bookmark = null;
 
 		try {
@@ -268,7 +268,7 @@ class BookmarkService {
 	 * @throws UrlParseError
 	 * @throws UserLimitExceededError
 	 */
-	public function update(string $userId, $id, string $url = null, string $title = null, string $description = null, array $tags = null, array $folders = null): ?Bookmark {
+	public function update(string $userId, $id, ?string $url = null, ?string $title = null, ?string $description = null, ?array $tags = null, ?array $folders = null): ?Bookmark {
 		/**
 		 * @var $bookmark Bookmark
 		 */
diff --git a/lib/Service/BookmarksParser.php b/lib/Service/BookmarksParser.php
index 2cb74fa9..8798075f 100644
--- a/lib/Service/BookmarksParser.php
+++ b/lib/Service/BookmarksParser.php
@@ -96,7 +96,7 @@ class BookmarksParser {
 	 * @return boolean
 	 */
 	public static function isValid($doctype): bool {
-		return self::DOCTYPE === $doctype;
+		return $doctype === self::DOCTYPE;
 	}
 
 	/**
@@ -117,7 +117,7 @@ class BookmarksParser {
 		if (empty($input)) {
 			throw new HtmlParseError("The input shouldn't be empty");
 		}
-		if (false === $document->loadHTML($input, LIBXML_PARSEHUGE)) {
+		if ($document->loadHTML($input, LIBXML_PARSEHUGE) === false) {
 			throw new HtmlParseError('The HTML value does not appear to be valid Netscape Bookmark File Format HTML.');
 		}
 		$this->xpath = new DOMXPath($document);
@@ -138,7 +138,7 @@ class BookmarksParser {
 	 *
 	 * @param DOMNode|null $node
 	 */
-	private function traverse(DOMNode $node = null): void {
+	private function traverse(?DOMNode $node = null): void {
 		$query = './*';
 		$entries = $this->xpath->query($query, $node ?: null);
 		if (!$entries) {
@@ -268,7 +268,7 @@ class BookmarksParser {
 		if ($this->useDateTimeObjects) {
 			if (isset($attributes['add_date'])) {
 				$added = new DateTime();
-				if (self::THOUSAND_YEARS < (int)$attributes['add_date']) {
+				if ((int)$attributes['add_date'] > self::THOUSAND_YEARS) {
 					// Google exports dates in miliseconds. This way we only lose the first year of UNIX Epoch.
 					// This is invalid once we hit 2970. So, quite a long time.
 					$added->setTimestamp((int) ($attributes['add_date'] / 1000));
@@ -297,7 +297,7 @@ class BookmarksParser {
 	private function getCurrentFolderTags(): array {
 		$tags = [];
 		array_walk_recursive($this->currentFolder, static function ($tag, $key) use (&$tags) {
-			if ('name' === $key) {
+			if ($key === 'name') {
 				$tags[] = $tag;
 			}
 		});
diff --git a/lib/Service/FaviconPreviewer.php b/lib/Service/FaviconPreviewer.php
index cf6b1c58..3e4b572e 100644
--- a/lib/Service/FaviconPreviewer.php
+++ b/lib/Service/FaviconPreviewer.php
@@ -134,7 +134,7 @@ class FaviconPreviewer implements IBookmarkPreviewer {
 		$contentType = $response->getHeader('Content-Type');
 
 		// Some HTPP Error occured :/
-		if (200 !== $response->getStatusCode()) {
+		if ($response->getStatusCode() !== 200) {
 			return null;
 		}
 
diff --git a/lib/Service/HtmlImporter.php b/lib/Service/HtmlImporter.php
index 39a61985..a203d3a5 100644
--- a/lib/Service/HtmlImporter.php
+++ b/lib/Service/HtmlImporter.php
@@ -90,7 +90,7 @@ class HtmlImporter {
 	 * @throws UserLimitExceededError
 	 * @throws HtmlParseError
 	 */
-	public function importFile($userId, string $file, int $rootFolder = null): array {
+	public function importFile($userId, string $file, ?int $rootFolder = null): array {
 		$content = file_get_contents($file);
 		return $this->import($userId, $content, $rootFolder);
 	}
@@ -113,7 +113,7 @@ class HtmlImporter {
 	 *
 	 * @psalm-return array{imported: list<array>, errors: array<array-key, mixed|string>}
 	 */
-	public function import($userId, string $content, int $rootFolderId = null): array {
+	public function import($userId, string $content, ?int $rootFolderId = null): array {
 		$imported = [];
 		$errors = [];
 
diff --git a/lib/Service/Previewers/DefaultBookmarkPreviewer.php b/lib/Service/Previewers/DefaultBookmarkPreviewer.php
index 641748dd..5d139868 100644
--- a/lib/Service/Previewers/DefaultBookmarkPreviewer.php
+++ b/lib/Service/Previewers/DefaultBookmarkPreviewer.php
@@ -80,7 +80,7 @@ class DefaultBookmarkPreviewer implements IBookmarkPreviewer {
 		$contentType = $response->getHeader('Content-Type');
 
 		// Some HTPP Error occured :/
-		if (200 !== $response->getStatusCode()) {
+		if ($response->getStatusCode() !== 200) {
 			return null;
 		}
 
diff --git a/lib/Service/Previewers/ScreeenlyBookmarkPreviewer.php b/lib/Service/Previewers/ScreeenlyBookmarkPreviewer.php
index f1c27729..92405b57 100644
--- a/lib/Service/Previewers/ScreeenlyBookmarkPreviewer.php
+++ b/lib/Service/Previewers/ScreeenlyBookmarkPreviewer.php
@@ -67,7 +67,7 @@ class ScreeenlyBookmarkPreviewer implements IBookmarkPreviewer {
 		if (!isset($bookmark)) {
 			return null;
 		}
-		if ('' === $this->apiKey) {
+		if ($this->apiKey === '') {
 			return null;
 		}
 		$url = $bookmark->getUrl();
@@ -97,7 +97,7 @@ class ScreeenlyBookmarkPreviewer implements IBookmarkPreviewer {
 		}
 
 		// Some HTPP Error occured :/
-		if (200 !== $response->getStatusCode()) {
+		if ($response->getStatusCode() !== 200) {
 			return null;
 		}
 
diff --git a/lib/Service/Previewers/ScreenshotMachineBookmarkPreviewer.php b/lib/Service/Previewers/ScreenshotMachineBookmarkPreviewer.php
index 8f6c6537..d645dbbc 100644
--- a/lib/Service/Previewers/ScreenshotMachineBookmarkPreviewer.php
+++ b/lib/Service/Previewers/ScreenshotMachineBookmarkPreviewer.php
@@ -84,7 +84,7 @@ class ScreenshotMachineBookmarkPreviewer implements IBookmarkPreviewer {
 				]
 			);
 			// Some HTPP Error occured :/
-			if (200 !== $response->getStatusCode()) {
+			if ($response->getStatusCode() !== 200) {
 				return null;
 			}
 			$body = $response->getBody();
diff --git a/lib/Service/Previewers/WebshotBookmarkPreviewer.php b/lib/Service/Previewers/WebshotBookmarkPreviewer.php
index 93afd6bf..7d79cd8b 100644
--- a/lib/Service/Previewers/WebshotBookmarkPreviewer.php
+++ b/lib/Service/Previewers/WebshotBookmarkPreviewer.php
@@ -93,7 +93,7 @@ class WebshotBookmarkPreviewer implements IBookmarkPreviewer {
 				'timeout' => self::HTTP_TIMEOUT,
 			]);
 			// Some HTPP Error occured :/
-			if (200 !== $response->getStatusCode()) {
+			if ($response->getStatusCode() !== 200) {
 				return null;
 			}
 			$data = json_decode($response->getBody(), true, 512, JSON_THROW_ON_ERROR);
@@ -101,7 +101,7 @@ class WebshotBookmarkPreviewer implements IBookmarkPreviewer {
 			// get it
 			$response = $this->client->get($this->apiUrl . $data->id);
 			// Some HTPP Error occured :/
-			if (200 !== $response->getStatusCode()) {
+			if ($response->getStatusCode() !== 200) {
 				return null;
 			}
 			$body = $response->getBody();