diff --git a/composer.json b/composer.json
index a341e37..36cdd45 100644
--- a/composer.json
+++ b/composer.json
@@ -11,6 +11,7 @@
     "sort-packages": true
   },
   "require": {
+    "beberlei/assert": "^3.3",
     "brianium/paratest": "^7",
     "clue/commander": "^v1.3.0",
     "ergebnis/phpunit-slow-test-detector": "^2",