diff --git a/composer.json b/composer.json
index 6ea5b41..2292336 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
   },
   "require-dev": {
     "phpunit/phpunit": "^5.4",
-    "graham-campbell/testbench": "^3.1"
+    "graham-campbell/testbench": "^3.1 || ^4.0"
   },
   "autoload": {
     "psr-4": {