diff --git a/composer.json b/composer.json
index 43e4a5f..a8294cd 100644
--- a/composer.json
+++ b/composer.json
@@ -31,7 +31,7 @@
     "ext-json": "*"
   },
   "require-dev": {
-    "phpunit/phpunit": "^8",
+    "phpunit/phpunit": "^7",
     "mockery/mockery": "^1",
     "phpstan/phpstan": "^0",
     "phpstan/phpstan-phpunit": "^0",
diff --git a/src/Pecee/SimpleRouter/Route/Route.php b/src/Pecee/SimpleRouter/Route/Route.php
index 0932f31..a8a5c37 100644
--- a/src/Pecee/SimpleRouter/Route/Route.php
+++ b/src/Pecee/SimpleRouter/Route/Route.php
@@ -30,6 +30,9 @@ abstract class Route implements IRoute
     protected $urlRegex = '/^%s\/?$/u';
     protected $group;
     protected $parent;
+    /**
+     * @var string|callable|null
+     */
     protected $callback;
     protected $defaultNamespace;