diff --git a/composer.json b/composer.json
index 44c245e..093c900 100644
--- a/composer.json
+++ b/composer.json
@@ -15,7 +15,7 @@
     ],
     "require": {
         "php": ">=5.5",
-        "guzzlehttp/guzzle": "^6.5.5"
+        "guzzlehttp/guzzle": "^6.0 || ^7.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^4.8 || ^5.7 || ^6.5"