diff -u b/src/AmazonPay.php b/src/AmazonPay.php
--- b/src/AmazonPay.php
+++ b/src/AmazonPay.php
@@ -213,7 +213,7 @@
       $next_state = $capture_now ? 'completed' : 'authorization';
       $payment->setState($next_state);
       // Authorizations can be captured for 30 days.
-      if ($capture_now === 'authorization') {
+      if (!$capture_now) {
         $expiration_timestamp = $this->time->getRequestTime() + 30 * 1440;
         $payment->setExpiresTime($expiration_timestamp);
       }