diff --git a/composer.json b/composer.json
index 42a3426..2920b43 100644
--- a/composer.json
+++ b/composer.json
@@ -22,7 +22,7 @@
     "require": {
         "php": ">=5.4.0",
         "99designs/http-signatures": ">=1.1.0 <3.0.0",
-        "guzzlehttp/guzzle": ">=4.2.0 <5.3.0"
+        "guzzlehttp/guzzle": ">=4.2.0 <=5.3.1"
     },
     "require-dev": {
         "phpunit/phpunit": "~4.1"