diff --git a/src/Backoff.php b/src/Backoff.php
index 39b874f..fee8a1f 100644
--- a/src/Backoff.php
+++ b/src/Backoff.php
@@ -307,7 +307,7 @@ public function wait($attempt)
             return;
         }
 
-        usleep($this->getWaitTime($attempt) * 1000);
+        usleep(intval($this->getWaitTime($attempt) * 1000));
     }
 
     /**