diff --git a/composer.json b/composer.json
index 4492a18..4e3b65f 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
     ],
     "require": {
         "php": "^7.1",
-        "guzzlehttp/guzzle": "^6.3.3",
+        "guzzlehttp/guzzle": "^6.3.3|^7.0",
         "guzzlehttp/promises": "^1.3",
         "guzzlehttp/psr7": "^1.5"
     },