diff --git a/composer.json b/composer.json
index c871f23b..6fbb7909 100644
--- a/composer.json
+++ b/composer.json
@@ -46,7 +46,11 @@
     "autoload": {
         "psr-4": {
             "Sabberworm\\CSS\\": "src/"
-        }
+        },
+        "files": [
+            "src/Rule/Rule.php",
+            "src/RuleSet/RuleContainer.php"
+        ]
     },
     "autoload-dev": {
         "psr-4": {
diff --git a/config/phpstan.neon b/config/phpstan.neon
index 84416ade..55ba682a 100644
--- a/config/phpstan.neon
+++ b/config/phpstan.neon
@@ -15,10 +15,6 @@ parameters:
     - %currentWorkingDirectory%/src/
     - %currentWorkingDirectory%/tests/
 
-  bootstrapFiles:
-    - %currentWorkingDirectory%/src/Rule/Rule.php
-    - %currentWorkingDirectory%/src/RuleSet/RuleContainer.php
-
   type_perfect:
     no_mixed_property: true
     no_mixed_caller: true