diff --git a/composer.json b/composer.json
index c43edaf..7ce0fd7 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,7 @@
         "php": "^7.0",
         "respect/validation": "^1.1",
         "ferfabricio/hydrator": "^2.0",
-        "guzzlehttp/guzzle": "~6.0",
+        "guzzlehttp/guzzle": "^6.0|^7.0",
         "maciejczyzewski/bottomline": "^0.2.0"
     },
     "require-dev": {