diff --git a/composer.json b/composer.json
index 7ff571c..2ff7669 100644
--- a/composer.json
+++ b/composer.json
@@ -11,7 +11,7 @@
     ],
     "require": {
         "php": ">=5.4",
-        "guzzlehttp/guzzle": "~5.0"
+        "guzzlehttp/guzzle": ">=4,<6"
     },
     "require-dev": {
         "phpunit/phpunit": "~4"