diff --git a/lib/private/Preview/BackgroundCleanupJob.php b/lib/private/Preview/BackgroundCleanupJob.php
index 319a9d4804f9a..85fe8d3303ef8 100644
--- a/lib/private/Preview/BackgroundCleanupJob.php
+++ b/lib/private/Preview/BackgroundCleanupJob.php
@@ -77,13 +77,13 @@ private function getOldPreviewLocations(): \Iterator {
 				$qb->expr()->castColumn('a.name', IQueryBuilder::PARAM_INT), 'b.fileid'
 			))
 			->where(
-				$qb->expr()->isNull('b.fileid')
-			)->andWhere(
-				$qb->expr()->eq('a.storage', $qb->createNamedParameter($this->previewFolder->getStorageId()))
-			)->andWhere(
-				$qb->expr()->eq('a.parent', $qb->createNamedParameter($this->previewFolder->getId()))
-			)->andWhere(
-				$qb->expr()->like('a.name', $qb->createNamedParameter('__%'))
+				$qb->expr()->andX(
+					$qb->expr()->isNull('b.fileid'),
+					$qb->expr()->eq('a.storage', $qb->createNamedParameter($this->previewFolder->getStorageId())),
+					$qb->expr()->eq('a.parent', $qb->createNamedParameter($this->previewFolder->getId())),
+					$qb->expr()->like('a.name', $qb->createNamedParameter('__%')),
+					$qb->expr()->eq('a.mimetype', $qb->createNamedParameter($this->mimeTypeLoader->getId('httpd/unix-directory')))
+				)
 			);
 
 		if (!$this->isCLI) {
diff --git a/tests/lib/Preview/BackgroundCleanupJobTest.php b/tests/lib/Preview/BackgroundCleanupJobTest.php
index 82f1979772800..0aad3121a7b7b 100644
--- a/tests/lib/Preview/BackgroundCleanupJobTest.php
+++ b/tests/lib/Preview/BackgroundCleanupJobTest.php
@@ -191,13 +191,44 @@ public function testOldPreviews() {
 		$f2 = $appdata->newFolder((string)PHP_INT_MAX - 1);
 		$f2->newFile('foo.jpg', 'foo');
 
+		/*
+		 * Cleanup of OldPreviewLocations should only remove numeric folders on AppData level,
+		 * therefore these files should stay untouched.
+		 */
+		$appdata->getFolder('/')->newFile('not-a-directory', 'foo');
+		$appdata->getFolder('/')->newFile('133742', 'bar');
+
 		$appdata = \OC::$server->getAppDataDir('preview');
+		// AppData::getDirectoryListing filters all non-folders
 		$this->assertSame(3, count($appdata->getDirectoryListing()));
+		try {
+			$appdata->getFolder('/')->getFile('not-a-directory');
+		} catch (NotFoundException) {
+			$this->fail('Could not find file \'not-a-directory\'');
+		}
+		try {
+			$appdata->getFolder('/')->getFile('133742');
+		} catch (NotFoundException) {
+			$this->fail('Could not find file \'133742\'');
+		}
 
 		$job = new BackgroundCleanupJob($this->timeFactory, $this->connection, $this->getRoot(), $this->mimeTypeLoader, true);
 		$job->run([]);
 
 		$appdata = \OC::$server->getAppDataDir('preview');
+
+		// Check if the files created above are still present
+		// Remember: AppData::getDirectoryListing filters all non-folders
 		$this->assertSame(0, count($appdata->getDirectoryListing()));
+		try {
+			$appdata->getFolder('/')->getFile('not-a-directory');
+		} catch (NotFoundException) {
+			$this->fail('Could not find file \'not-a-directory\'');
+		}
+		try {
+			$appdata->getFolder('/')->getFile('133742');
+		} catch (NotFoundException) {
+			$this->fail('Could not find file \'133742\'');
+		}
 	}
 }