diff --git a/lib/private/Files/Config/UserMountCache.php b/lib/private/Files/Config/UserMountCache.php
index de85a99cebc..fe3b9ea64ad 100644
--- a/lib/private/Files/Config/UserMountCache.php
+++ b/lib/private/Files/Config/UserMountCache.php
@@ -467,16 +467,8 @@ class UserMountCache implements IUserMountCache {
 	public function getUsedSpaceForUsers(array $users) {
 		$builder = $this->connection->getQueryBuilder();
 
-		$slash = $builder->createNamedParameter('/');
-
-		$mountPoint = $builder->func()->concat(
-			$builder->func()->concat($slash, 'user_id'),
-			$slash
-		);
-
-		$userIds = array_map(function (IUser $user) {
-			return $user->getUID();
-		}, $users);
+		$mountPointHashes = array_map(static fn (IUser $user) => hash('xxh128', '/' . $user->getUID() . '/'), $users);
+		$userIds = array_map(static fn (IUser $user) => $user->getUID(), $users);
 
 		$query = $builder->select('m.user_id', 'f.size')
 			->from('mounts', 'm')
@@ -485,7 +477,7 @@ class UserMountCache implements IUserMountCache {
 					$builder->expr()->eq('m.storage_id', 'f.storage'),
 					$builder->expr()->eq('f.path_hash', $builder->createNamedParameter(md5('files')))
 				))
-			->where($builder->expr()->eq('m.mount_point', $mountPoint))
+			->where($builder->expr()->in('m.mount_point_hash', $builder->createNamedParameter($mountPointHashes, IQueryBuilder::PARAM_STR_ARRAY)))
 			->andWhere($builder->expr()->in('m.user_id', $builder->createNamedParameter($userIds, IQueryBuilder::PARAM_STR_ARRAY)));
 
 		$result = $query->executeQuery();