diff --git a/composer.json b/composer.json
index 3db0bcf..5382a33 100644
--- a/composer.json
+++ b/composer.json
@@ -11,6 +11,7 @@
         "php": "^7.1"
     },
     "require-dev": {
+        "behat/mink-extension": "^2.3.1",
         "composer/installers": "~1.5",
         "consolidation/robo": "~1.4",
         "consolidation/annotated-command": "^2.8.2",