diff --git a/src/Bundle/ChillWopiBundle/src/Service/Wopi/ChillDocumentLockManager.php b/src/Bundle/ChillWopiBundle/src/Service/Wopi/ChillDocumentLockManager.php
index d4338b208..e6889778c 100644
--- a/src/Bundle/ChillWopiBundle/src/Service/Wopi/ChillDocumentLockManager.php
+++ b/src/Bundle/ChillWopiBundle/src/Service/Wopi/ChillDocumentLockManager.php
@@ -52,7 +52,16 @@ class ChillDocumentLockManager implements DocumentLockManagerInterface
 
     public function hasLock(Document $document, RequestInterface $request): bool
     {
-        return $this->redis->exists($this->getCacheId($document)) > 0;
+        $r = $this->redis->exists($this->getCacheId($document));
+
+        if (is_bool($r)) {
+            return $r;
+        }
+        if (is_int($r)) {
+            return $r > 0;
+        }
+
+        throw new \RuntimeException('data type not supported');
     }
 
     public function setLock(Document $document, string $lockId, RequestInterface $request): bool