diff --git a/.travis.yml b/.travis.yml
index 1f64ea7..ace60a5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,6 +20,11 @@ jobs:
         - "composer test:phpunit -- --verbose"
         # - "composer test:cs -- -s"
         - "composer test:phpstan -- --ansi --memory-limit=1G --no-progress"
+    - name: "With lowest deps"
+      php: "7.4"
+      install:
+        - "composer update --no-interaction --prefer-lowest"
+        - "composer update --no-interaction --with-all-dependencies szepeviktor/phpcs-psr-12-neutron-hybrid-ruleset 'php-stubs/wordpress-stubs:^6.1'"
 
 cache:
   directories:
diff --git a/composer.json b/composer.json
index 8c17699..23f5942 100644
--- a/composer.json
+++ b/composer.json
@@ -21,8 +21,8 @@
         "dealerdirect/phpcodesniffer-composer-installer": "^0.7",
         "php-parallel-lint/php-parallel-lint": "^1.1",
         "phpstan/phpstan-strict-rules": "^1.2",
-        "phpunit/phpunit": "^8 || ^9",
-        "szepeviktor/phpcs-psr-12-neutron-hybrid-ruleset": "^0.6"
+        "phpunit/phpunit": "^8.0 || ^9.0",
+        "szepeviktor/phpcs-psr-12-neutron-hybrid-ruleset": "^0.6.1"
     },
     "autoload-dev": {
         "classmap": [
diff --git a/src/WpThemeGetDynamicMethodReturnTypeExtension.php b/src/WpThemeGetDynamicMethodReturnTypeExtension.php
index b463be7..39e739d 100644
--- a/src/WpThemeGetDynamicMethodReturnTypeExtension.php
+++ b/src/WpThemeGetDynamicMethodReturnTypeExtension.php
@@ -28,7 +28,7 @@ class WpThemeGetDynamicMethodReturnTypeExtension implements \PHPStan\Type\Dynami
      *
      * @var list<string>
      */
-    private static $headers = [
+    protected static $headers = [
         'Name',
         'ThemeURI',
         'Description',