diff --git a/composer.json b/composer.json
index e3dea930..00c6b13e 100644
--- a/composer.json
+++ b/composer.json
@@ -27,6 +27,9 @@
         "php": ">=5.3",
         "php-flasher/flasher": "dev-main"
     },
+    "require-dev": {
+        "phpunit/phpunit": "^4.8|^5.0|^6.0|^7.0|^8.0|^9.0"
+    },
     "autoload": {
         "psr-4": {
             "Flasher\\Toastr\\Prime\\": ""