diff --git a/lib/Service/ApprovalService.php b/lib/Service/ApprovalService.php
index 197918b7..2c128cf8 100644
--- a/lib/Service/ApprovalService.php
+++ b/lib/Service/ApprovalService.php
@@ -31,6 +31,9 @@
 use Sabre\DAV\INode;
 use Sabre\DAV\PropFind;
 
+/**
+ * @psalm-import-type Rule from RuleService
+ */
 class ApprovalService {
 
 	public function __construct(
@@ -164,7 +167,7 @@ public function getUserRules(string $userId, string $role = 'requesters', ?int $
 	 * Check if a user is authorized to approve or request by a given rule
 	 *
 	 * @param string $userId
-	 * @param array $rule
+	 * @param Rule $rule
 	 * @param string $role
 	 * @return bool
 	 */
@@ -180,7 +183,7 @@ private function userIsAuthorizedByRule(string $userId, array $rule, string $rol
 		}));
 
 		// if user is in rule's user list
-		if (in_array($userId, $ruleUserIds)) {
+		if (in_array($userId, $ruleUserIds, true)) {
 			return true;
 		} else {
 			// if user is member of one rule's group list
@@ -285,15 +288,15 @@ public function getApprovalState(int $fileId, ?string $userId, bool $userHasAcce
 		$rules = $this->ruleService->getRules();
 
 		// Get all tags a file has to prevent needing to check for each tag in every rule
-		$tags = $this->tagObjectMapper->getTagIdsForObjects([$fileId], 'files');
-		if (!array_key_exists($fileId, $tags)) {
+		$tags = $this->tagObjectMapper->getTagIdsForObjects([(string)$fileId], 'files');
+		if (!array_key_exists((string)$fileId, $tags)) {
 			return ['state' => Application::STATE_NOTHING];
 		}
-		$tags = $tags[$fileId];
+		$tags = array_map(static fn ($tag): string => (string)$tag, $tags[(string)$fileId]);
 
 		// first check if it's approvable
 		foreach ($rules as $id => $rule) {
-			if (in_array($rule['tagPending'], $tags)
+			if (in_array($rule['tagPending'], $tags, true)
 				&& $this->userIsAuthorizedByRule($userId, $rule, 'approvers')) {
 				return [
 					'state' => Application::STATE_APPROVABLE,
@@ -304,7 +307,7 @@ public function getApprovalState(int $fileId, ?string $userId, bool $userHasAcce
 
 		// then check pending in priority
 		foreach ($rules as $id => $rule) {
-			if (in_array($rule['tagPending'], $tags)) {
+			if (in_array($rule['tagPending'], $tags, true)) {
 				return [
 					'state' => Application::STATE_PENDING,
 					'rule' => $rule,
@@ -313,7 +316,7 @@ public function getApprovalState(int $fileId, ?string $userId, bool $userHasAcce
 		}
 		// then rejected
 		foreach ($rules as $id => $rule) {
-			if (in_array($rule['tagRejected'], $tags)) {
+			if (in_array($rule['tagRejected'], $tags, true)) {
 				return [
 					'state' => Application::STATE_REJECTED,
 					'rule' => $rule,
@@ -322,7 +325,7 @@ public function getApprovalState(int $fileId, ?string $userId, bool $userHasAcce
 		}
 		// then approved
 		foreach ($rules as $id => $rule) {
-			if (in_array($rule['tagApproved'], $tags)) {
+			if (in_array($rule['tagApproved'], $tags, true)) {
 				return [
 					'state' => Application::STATE_APPROVED,
 					'rule' => $rule,
@@ -502,7 +505,7 @@ public function requestViaTagAssignment(int $fileId, int $ruleId, string $reques
 	 * Share file with everybody who can approve with given rule and have no access yet
 	 *
 	 * @param int $fileId
-	 * @param array $rule
+	 * @param Rule $rule
 	 * @param string $userId
 	 * @return array list of created shares
 	 * @throws \OCP\Files\NotPermittedException
@@ -626,7 +629,7 @@ public function getRuleAuthorizedUserIds(array $rule, string $role = 'approvers'
 		$ruleUserIds = [];
 		foreach ($rule[$role] as $approver) {
 			if ($approver['type'] === 'user') {
-				if (!in_array($approver['entityId'], $ruleUserIds)) {
+				if (!in_array($approver['entityId'], $ruleUserIds, true)) {
 					$ruleUserIds[] = $approver['entityId'];
 				}
 			} elseif ($approver['type'] === 'group') {
@@ -634,7 +637,7 @@ public function getRuleAuthorizedUserIds(array $rule, string $role = 'approvers'
 				if ($this->groupManager->groupExists($groupId)) {
 					$users = $this->groupManager->get($groupId)->getUsers();
 					foreach ($users as $user) {
-						if ($user instanceof IUser && !in_array($user->getUID(), $ruleUserIds)) {
+						if ($user instanceof IUser && !in_array($user->getUID(), $ruleUserIds, true)) {
 							$ruleUserIds[] = $user->getUID();
 						}
 					}
@@ -650,7 +653,7 @@ public function getRuleAuthorizedUserIds(array $rule, string $role = 'approvers'
 							continue;
 						}
 						$memberUserId = $member->getUserId();
-						if (!in_array($memberUserId, $ruleUserIds)) {
+						if (!in_array($memberUserId, $ruleUserIds, true)) {
 							$ruleUserIds[] = $memberUserId;
 						}
 					}
@@ -678,7 +681,7 @@ public function handleTagAssignmentEvent(int $fileId, array $tags): void {
 		$rules = $this->ruleService->getRules();
 		foreach ($rules as $id => $rule) {
 			// rule matches tags
-			if (in_array($rule['tagPending'], $tags)) {
+			if (in_array($rule['tagPending'], $tags, true)) {
 				$ruleInvolded = $rule;
 				break;
 			}
@@ -722,7 +725,7 @@ public function handleTagAssignmentEvent(int $fileId, array $tags): void {
 	 * Send it to all users who are authorized to approve it
 	 *
 	 * @param int $fileId
-	 * @param array $rule
+	 * @param Rule $rule
 	 * @param string $requestUserId
 	 * @return void
 	 */
@@ -731,7 +734,7 @@ public function sendRequestNotification(int $fileId, array $rule, string $reques
 		$rulesUserIds = [];
 		$thisRuleUserIds = $this->getRuleAuthorizedUserIds($rule, 'approvers');
 		foreach ($thisRuleUserIds as $userId) {
-			if (!in_array($userId, $rulesUserIds)) {
+			if (!in_array($userId, $rulesUserIds, true)) {
 				$rulesUserIds[] = $userId;
 			}
 		}
diff --git a/lib/Service/RuleService.php b/lib/Service/RuleService.php
index b78394ae..ea0028a0 100644
--- a/lib/Service/RuleService.php
+++ b/lib/Service/RuleService.php
@@ -16,6 +16,18 @@
 
 use OCP\IUserManager;
 
+/**
+ * @psalm-type Rule = array{
+ *      id: int,
+ *      tagPending: string,
+ *      tagApproved: string,
+ *      tagRejected: string,
+ *      description: string,
+ *      approvers: array,
+ *      requesters: array,
+ *      unapproveWhenModified: bool,
+ *  }
+ */
 class RuleService {
 	/** @var array */
 	private $strTypeToInt;
@@ -318,7 +330,7 @@ public function deleteRule(int $id): array {
 	/**
 	 * Get a rule by id
 	 * @param int $id the rule id
-	 * @return array|null the rule or null if not found
+	 * @return Rule|null the rule or null if not found
 	 */
 	public function getRule(int $id): ?array {
 		$rule = null;
@@ -331,9 +343,9 @@ public function getRule(int $id): ?array {
 			);
 		$req = $qb->executeQuery();
 		while ($row = $req->fetch()) {
-			$tagPending = (int)$row['tag_pending'];
-			$tagApproved = (int)$row['tag_approved'];
-			$tagRejected = (int)$row['tag_rejected'];
+			$tagPending = (string)$row['tag_pending'];
+			$tagApproved = (string)$row['tag_approved'];
+			$tagRejected = (string)$row['tag_rejected'];
 			$description = $row['description'];
 			$rule = [
 				'id' => $id,
@@ -362,7 +374,7 @@ public function getRule(int $id): ?array {
 	/**
 	 * Get all rules
 	 *
-	 * @return array
+	 * @return array<int, Rule>
 	 */
 	public function getRules(): array {
 		if ($this->cachedRules === null) {
@@ -374,9 +386,9 @@ public function getRules(): array {
 			$req = $qb->executeQuery();
 			while ($row = $req->fetch()) {
 				$id = (int)$row['id'];
-				$tagPending = (int)$row['tag_pending'];
-				$tagApproved = (int)$row['tag_approved'];
-				$tagRejected = (int)$row['tag_rejected'];
+				$tagPending = (string)$row['tag_pending'];
+				$tagApproved = (string)$row['tag_approved'];
+				$tagRejected = (string)$row['tag_rejected'];
 				$description = $row['description'];
 				$rules[$id] = [
 					'id' => $id,
diff --git a/tests/unit/Service/ApprovalServiceTest.php b/tests/unit/Service/ApprovalServiceTest.php
index 001bffc4..8c539c85 100644
--- a/tests/unit/Service/ApprovalServiceTest.php
+++ b/tests/unit/Service/ApprovalServiceTest.php
@@ -28,49 +28,19 @@
 use Psr\Log\LoggerInterface;
 
 class ApprovalServiceTest extends TestCase {
-
-	/**
-	 * @var RuleService
-	 */
-	private $ruleService;
-	/**
-	 * @var ApprovalService
-	 */
-	private $approvalService;
-	/**
-	 * @var UtilsService
-	 */
-	private $utilsService;
-	/**
-	 * @var IRootFolder
-	 */
-	private $root;
-	/**
-	 * @var int
-	 */
-	private $idTagPending1;
-	/**
-	 * @var int
-	 */
-	private $idTagApproved1;
-	/**
-	 * @var int
-	 */
-	private $idTagRejected1;
-	/**
-	 * @var int
-	 */
-	private $idRule1;
-	/**
-	 * @var ISystemTagObjectMapper
-	 */
-	private $tagObjectMapper;
-	/**
-	 * @var string[][]
-	 */
-	private $approvers1;
-	private $requesters1;
-	private $description1;
+	private RuleService $ruleService;
+	private ApprovalService $approvalService;
+	private UtilsService $utilsService;
+	private IRootFolder $root;
+	private int $idTagPending1;
+	private int $idTagApproved1;
+	private int $idTagRejected1;
+	private int $idRule1;
+	private ISystemTagObjectMapper $tagObjectMapper;
+	/** @var string[][] */
+	private array $approvers1;
+	private array $requesters1;
+	private string $description1;
 
 	public static function setUpBeforeClass(): void {
 		$app = new Application();
@@ -271,7 +241,7 @@ public function testGetRuleAuthorizedUserIds() {
 		$this->assertEquals('user1', $uidRequesters[0]);
 	}
 
-	public function testGetApprovalState() {
+	public function testGetApprovalState(): void {
 		$uf = $this->root->getUserFolder('user1');
 		$file1 = $uf->newFile('file1.txt', 'content');
 		$state = $this->approvalService->getApprovalState($file1->getId(), 'user1');