diff --git a/src/JWT.php b/src/JWT.php
index 421c42c2..c83ff099 100644
--- a/src/JWT.php
+++ b/src/JWT.php
@@ -439,7 +439,7 @@ private static function getKey(
             return $keyOrKeyArray;
         }
 
-        if (!isset($kid)) {
+        if (empty($kid) && $kid !== '0') {
             throw new UnexpectedValueException('"kid" empty, unable to lookup correct key');
         }