diff --git a/composer.json b/composer.json
index 8985858..f667a5b 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
     ],
     "require": {
         "php": ">=5.5.9",
-        "symfony/process": "^2.7 || ^3.0"
+        "symfony/process": "^2.7 || ^3.0" || "^4.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^4.8"