diff --git a/composer.json b/composer.json
index ecde055..6921977 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
     "minimum-stability": "stable",
     "require": {},
     "require-dev": {
-        "phpunit/phpunit": "^5.0"
+        "phpunit/phpunit": "^4.8 || ^5.4"
     },
     "autoload": {
         "psr-4": {
diff --git a/composer.lock b/composer.lock
index 3d07fe3..2564692 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,8 +4,8 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "hash": "cf8312244a9d5d88f090d82f5ff427db",
-    "content-hash": "9ff1027034b0ad865926cd9c42bef394",
+    "hash": "65a3c489a4c7cb0354fa7762c130a65f",
+    "content-hash": "b4653f0918896a9ec7a8b8ea18ec29ac",
     "packages": [],
     "packages-dev": [
         {