diff --git a/lib/private/Lock/MemcacheLockingProvider.php b/lib/private/Lock/MemcacheLockingProvider.php
index 6b01f0aafc..439894e901 100644
--- a/lib/private/Lock/MemcacheLockingProvider.php
+++ b/lib/private/Lock/MemcacheLockingProvider.php
@@ -61,7 +61,7 @@ class MemcacheLockingProvider extends AbstractLockingProvider {
 	public function isLocked(string $path, int $type): bool {
 		$lockValue = $this->memcache->get($path);
 		if ($type === self::LOCK_SHARED) {
-			return $lockValue > 0;
+			return is_int($lockValue) && $lockValue > 0;
 		} elseif ($type === self::LOCK_EXCLUSIVE) {
 			return $lockValue === 'exclusive';
 		} else {