diff --git a/lib/ACL/ACLManager.php b/lib/ACL/ACLManager.php
index 3aad0ad80..539708c27 100644
--- a/lib/ACL/ACLManager.php
+++ b/lib/ACL/ACLManager.php
@@ -64,7 +64,7 @@ private function getRules(int $storageId, array $paths, bool $cache = true): arr
 
 		$nonCachedPaths = array_filter($paths, fn (string $path): bool => !isset($rules[$path]));
 
-		if (!empty($nonCachedPaths)) {
+		if ($nonCachedPaths !== []) {
 			$newRules = $this->ruleManager->getRulesForFilesByPath($this->user, $storageId, $nonCachedPaths);
 			foreach ($newRules as $path => $rulesForPath) {
 				if ($cache) {
diff --git a/lib/ACL/Rule.php b/lib/ACL/Rule.php
index 874be5a8d..125602216 100644
--- a/lib/ACL/Rule.php
+++ b/lib/ACL/Rule.php
@@ -140,7 +140,7 @@ public static function xmlDeserialize(Reader $reader): Rule {
 			throw new \RuntimeException(self::MAPPING_TYPE . ' is not a string.');
 		}
 
-		if (!in_array($mappingType, ['user', 'group', 'circle'])) {
+		if (!in_array($mappingType, ['user', 'group', 'circle'], true)) {
 			throw new \RuntimeException(self::MAPPING_TYPE . ' does not have a valid value.');
 		}
 
diff --git a/lib/ACL/RuleManager.php b/lib/ACL/RuleManager.php
index 268ec0b12..d1f635fd4 100644
--- a/lib/ACL/RuleManager.php
+++ b/lib/ACL/RuleManager.php
@@ -29,7 +29,7 @@ public function __construct(
 	 * @param array{mapping_type?: 'user'|'group'|'dummy'|'circle'|null, mapping_id: string, fileid: int|string, mask: int|string, permissions: int|string} $data
 	 */
 	private function createRule(array $data): ?Rule {
-		if (empty($data['mapping_type'])) {
+		if (!isset($data['mapping_type'])) {
 			return null;
 		}
 		$mapping = $this->userMappingManager->mappingFromId($data['mapping_type'], $data['mapping_id']);
@@ -116,7 +116,7 @@ public function getRulesForFilesByPath(IUser $user, int $storageId, array $fileP
 	 */
 	public function getRulesForFilesByIds(IUser $user, array $fileIds): array {
 		$userMappings = $this->userMappingManager->getMappingsForUser($user);
-		if (empty($userMappings)) {
+		if ($userMappings === []) {
 			return [];
 		}
 
@@ -144,7 +144,7 @@ public function getRulesForFilesByIds(IUser $user, array $fileIds): array {
 	 */
 	public function getRulesForFilesByParent(IUser $user, int $storageId, int $parentId): array {
 		$userMappings = $this->userMappingManager->getMappingsForUser($user);
-		if (empty($userMappings)) {
+		if ($userMappings === []) {
 			return [];
 		}
 
@@ -312,7 +312,7 @@ public function getAllRulesForPrefix(int $storageId, string $prefix): array {
 	 */
 	public function getRulesForPrefix(IUser $user, int $storageId, string $prefix): array {
 		$userMappings = $this->userMappingManager->getMappingsForUser($user);
-		if (empty($userMappings)) {
+		if ($userMappings === []) {
 			return [];
 		}
 
diff --git a/lib/Command/Create.php b/lib/Command/Create.php
index a8c56c029..31f84dfec 100644
--- a/lib/Command/Create.php
+++ b/lib/Command/Create.php
@@ -40,7 +40,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 		$name = $this->folderManager->trimMountpoint($name);
 
 		// Check if the folder name is valid
-		if (empty($name)) {
+		if ($name === '') {
 			$output->writeln('<error>Folder name cannot be empty</error>');
 			return 1;
 		}
diff --git a/lib/Command/Rename.php b/lib/Command/Rename.php
index dccf76309..7bff3675e 100644
--- a/lib/Command/Rename.php
+++ b/lib/Command/Rename.php
@@ -38,7 +38,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 
 		// Check if the new name is valid
 		$name = $this->folderManager->trimMountpoint($name);
-		if (empty($name)) {
+		if ($name === '') {
 			$output->writeln('<error>Folder name cannot be empty</error>');
 			return 1;
 		}
diff --git a/lib/Folder/FolderManager.php b/lib/Folder/FolderManager.php
index 46853da25..9f394115a 100644
--- a/lib/Folder/FolderManager.php
+++ b/lib/Folder/FolderManager.php
@@ -528,7 +528,7 @@ public function canManageACL(int $folderId, IUser $user, bool $excludeAdmins = f
 	}
 
 	private function computeCanManageACL(int $folderId, IUser $user, bool $excludeAdmins): bool {
-		$userId = $user->getUId();
+		$userId = $user->getUID();
 		if (!$excludeAdmins && $this->groupManager->isAdmin($userId)) {
 			return true;
 		}
@@ -1536,12 +1536,12 @@ public function updateOverwriteHomeFolders(): void {
 		$appIdsList = $this->appConfig->getValueArray('files', 'overwrites_home_folders');
 
 		if ($this->hasHomeFolderOverwriteMount()) {
-			if (!in_array(Application::APP_ID, $appIdsList)) {
+			if (!in_array(Application::APP_ID, $appIdsList, true)) {
 				$appIdsList[] = Application::APP_ID;
 				$this->appConfig->setValueArray('files', 'overwrites_home_folders', $appIdsList);
 			}
 		} else {
-			if (in_array(Application::APP_ID, $appIdsList)) {
+			if (in_array(Application::APP_ID, $appIdsList, true)) {
 				$appIdsList = array_values(array_filter($appIdsList, fn ($v): bool => $v !== Application::APP_ID));
 				$this->appConfig->setValueArray('files', 'overwrites_home_folders', $appIdsList);
 			}
diff --git a/lib/Mount/GroupMountPoint.php b/lib/Mount/GroupMountPoint.php
index c3493be4d..a6e56b663 100644
--- a/lib/Mount/GroupMountPoint.php
+++ b/lib/Mount/GroupMountPoint.php
@@ -54,7 +54,7 @@ public function getSourcePath(): string {
 		$storage = $this->storage;
 		if ($storage && $storage->instanceOfStorage(Jail::class)) {
 			/** @var Jail $storage */
-			return $storage->getUnJailedPath('');
+			return $storage->getUnjailedPath('');
 		}
 
 		return '';
diff --git a/lib/Mount/MountProvider.php b/lib/Mount/MountProvider.php
index a84777dc2..60227986f 100644
--- a/lib/Mount/MountProvider.php
+++ b/lib/Mount/MountProvider.php
@@ -72,7 +72,7 @@ public function getMountsForUser(IUser $user, IStorageFactory $loader): array {
 		return array_map(function (FolderDefinitionWithPermissions $folder) use ($user, $loader, $conflicts, $aclManager, $rootRules): IMountPoint {
 			// check for existing files in the user home and rename them if needed
 			$originalFolderName = $folder->mountPoint;
-			if (in_array($originalFolderName, $conflicts)) {
+			if (in_array($originalFolderName, $conflicts, true)) {
 				/** @var IStorage $userStorage */
 				$userStorage = $this->mountProviderCollection->getHomeMountForUser($user)->getStorage();
 				$userCache = $userStorage->getCache();
diff --git a/lib/Service/ApplicationService.php b/lib/Service/ApplicationService.php
index a5cffcae2..ebdd5b2e6 100644
--- a/lib/Service/ApplicationService.php
+++ b/lib/Service/ApplicationService.php
@@ -24,6 +24,6 @@ public function __construct(
 	public function checkAppsInstalled(): bool {
 		$diffApps = array_diff(Application::APPS_USE_GROUPFOLDERS, $this->appManager->getEnabledApps());
 
-		return empty($diffApps);
+		return $diffApps === [];
 	}
 }
diff --git a/lib/Service/FoldersFilter.php b/lib/Service/FoldersFilter.php
index 6bfba5585..b0e12fd03 100644
--- a/lib/Service/FoldersFilter.php
+++ b/lib/Service/FoldersFilter.php
@@ -35,10 +35,10 @@ public function getForApiUser(array $folders): array {
 		return array_filter($folders, function (array $folder) use ($user): bool {
 			foreach ($folder['manage'] as $manager) {
 				if ($manager['type'] === 'group') {
-					if ($this->groupManager->isInGroup($user->getUid(), $manager['id'])) {
+					if ($this->groupManager->isInGroup($user->getUID(), $manager['id'])) {
 						return true;
 					}
-				} elseif ($manager['id'] === $user->getUid()) {
+				} elseif ($manager['id'] === $user->getUID()) {
 					return true;
 				}
 			}
diff --git a/lib/Versions/VersionsBackend.php b/lib/Versions/VersionsBackend.php
index 2d6f58a15..c232f7f8e 100644
--- a/lib/Versions/VersionsBackend.php
+++ b/lib/Versions/VersionsBackend.php
@@ -112,7 +112,7 @@ public function getVersionsForFile(IUser $user, FileInfo $file): array {
 				throw new RuntimeException('Failed to get id of file.');
 			}
 			$versionEntity->setFileId($fileId);
-			$versionEntity->setTimestamp($file->getMTime());
+			$versionEntity->setTimestamp($file->getMtime());
 			$versionEntity->setSize($file->getSize());
 			$versionEntity->setMimetype($this->mimeTypeLoader->getId($file->getMimetype()));
 			$versionEntity->setDecodedMetadata([]);
@@ -135,7 +135,7 @@ public function getVersionsForFile(IUser $user, FileInfo $file): array {
 				// This means that the name of some versions is the exact mtime of the next version. This behavior is now fixed.
 				// To prevent occasional conflicts between the last version and the current one, we decrement the last version mtime.
 				$mtime = (int)$version->getName();
-				if ($mtime === $file->getMTime()) {
+				if ($mtime === $file->getMtime()) {
 					$versionEntity->setTimestamp($mtime - 1);
 					$version->move($version->getParent()->getPath() . '/' . ($mtime - 1));
 				} else {
@@ -427,7 +427,7 @@ public function createVersionEntity(File $file): null {
 			$versionEntity->setFileId($fileId);
 			$versionEntity->setTimestamp($timestamp);
 			$versionEntity->setSize($file->getSize());
-			$versionEntity->setMimetype($this->mimeTypeLoader->getId($file->getMimetype()));
+			$versionEntity->setMimetype($this->mimeTypeLoader->getId($file->getMimeType()));
 			$versionEntity->setDecodedMetadata([]);
 			$this->groupVersionsMapper->insert($versionEntity);
 		}
@@ -494,7 +494,7 @@ public function importVersionsForFile(IUser $user, Node $source, Node $target, a
 			$versionEntity->setFileId($target->getId());
 			$versionEntity->setTimestamp($version->getTimestamp());
 			$versionEntity->setSize($version->getSize());
-			$versionEntity->setMimetype($this->mimeTypeLoader->getId($version->getMimetype()));
+			$versionEntity->setMimetype($this->mimeTypeLoader->getId($version->getMimeType()));
 			if ($version instanceof IMetadataVersion) {
 				$versionEntity->setDecodedMetadata($version->getMetadata());
 			}
diff --git a/phpstan.neon b/phpstan.neon
index e746422c4..50bad73ae 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,5 +1,8 @@
 # SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
 # SPDX-License-Identifier: AGPL-3.0-or-later
+includes:
+    - vendor-bin/phpstan/vendor/phpstan/phpstan-strict-rules/rules.neon
+
 parameters:
 	level: 10
 	phpVersion:
@@ -9,6 +12,12 @@ parameters:
 		- lib
 		- templates
 		- tests
+	strictRules:
+		allRules: false
+		strictFunctionCalls: true
+		disallowedLooseComparison: true
+		disallowedEmpty: true
+		disallowedImplicitArrayCreation: true
 	excludePaths:
 		- tests/stubs
 	scanDirectories:
diff --git a/tests/ACL/ACLManagerTest.php b/tests/ACL/ACLManagerTest.php
index c78382e11..f526119e1 100644
--- a/tests/ACL/ACLManagerTest.php
+++ b/tests/ACL/ACLManagerTest.php
@@ -48,7 +48,7 @@ protected function setUp(): void {
 				/** @var string[] $paths */
 				$this->requestedPaths = array_values(array_merge($this->requestedPaths, $paths));
 				$rules = array_fill_keys($paths, []);
-				$actualRules = array_filter($this->rules, fn (string $path): bool => array_search($path, $paths) !== false, ARRAY_FILTER_USE_KEY);
+				$actualRules = array_filter($this->rules, fn (string $path): bool => array_search($path, $paths, true) !== false, ARRAY_FILTER_USE_KEY);
 
 				return array_merge($rules, $actualRules);
 			});
diff --git a/vendor-bin/phpstan/composer.json b/vendor-bin/phpstan/composer.json
index 5111129c6..602e266b1 100644
--- a/vendor-bin/phpstan/composer.json
+++ b/vendor-bin/phpstan/composer.json
@@ -1,5 +1,6 @@
 {
     "require-dev": {
-        "phpstan/phpstan": "^2.2"
+        "phpstan/phpstan": "^2.2",
+        "phpstan/phpstan-strict-rules": "^2.0"
     }
 }
diff --git a/vendor-bin/phpstan/composer.lock b/vendor-bin/phpstan/composer.lock
index 53d98e585..b2bf85268 100644
--- a/vendor-bin/phpstan/composer.lock
+++ b/vendor-bin/phpstan/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "a51b3f39b291c98954d42def89bce21e",
+    "content-hash": "1e46f1af4fc47e311cc3d5016311ba28",
     "packages": [],
     "packages-dev": [
         {
@@ -70,6 +70,58 @@
                 }
             ],
             "time": "2026-08-22T07:38:16+00:00"
+        },
+        {
+            "name": "phpstan/phpstan-strict-rules",
+            "version": "2.0.12",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/phpstan/phpstan-strict-rules.git",
+                "reference": "2bc5ae19ae965663b62ac907ee6342c3903ec93b"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/phpstan/phpstan-strict-rules/zipball/2bc5ae19ae965663b62ac907ee6342c3903ec93b",
+                "reference": "2bc5ae19ae965663b62ac907ee6342c3903ec93b",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.4 || ^8.0",
+                "phpstan/phpstan": "^2.1.52"
+            },
+            "require-dev": {
+                "php-parallel-lint/php-parallel-lint": "^1.2",
+                "phpstan/phpstan-deprecation-rules": "^2.0",
+                "phpstan/phpstan-phpunit": "^2.0",
+                "phpunit/phpunit": "^9.6",
+                "shipmonk/name-collision-detector": "^2.1"
+            },
+            "type": "phpstan-extension",
+            "extra": {
+                "phpstan": {
+                    "includes": [
+                        "rules.neon"
+                    ]
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "PHPStan\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "description": "Extra strict and opinionated rules for PHPStan",
+            "keywords": [
+                "static analysis"
+            ],
+            "support": {
+                "issues": "https://github.com/phpstan/phpstan-strict-rules/issues",
+                "source": "https://github.com/phpstan/phpstan-strict-rules/tree/2.0.12"
+            },
+            "time": "2026-07-19T07:24:06+00:00"
         }
     ],
     "aliases": [],