diff --git a/src/Unirest/Request.php b/src/Unirest/Request.php
index b49780d..a890ee1 100755
--- a/src/Unirest/Request.php
+++ b/src/Unirest/Request.php
@@ -555,7 +555,7 @@ private static function encodeUrl($url)
             $query = '?' . http_build_query(self::getArrayFromQuerystring($query));
         }
 
-        if ($port && $port[0] !== ':') {
+        if ($port && ((string)$port)[0] !== ':') {
             $port = ':' . $port;
         }