diff --git a/tests/src/Unit/ChainPermissionCalculatorTest.php b/tests/src/Unit/ChainPermissionCalculatorTest.php
index 9d37b62290dd08a6c295ed17dfc2208b8e3ba120..2218e7f4a515a6407b5a60f97290d16e20987cf3 100644
--- a/tests/src/Unit/ChainPermissionCalculatorTest.php
+++ b/tests/src/Unit/ChainPermissionCalculatorTest.php
@@ -288,10 +288,10 @@ class ChainPermissionCalculatorTest extends UnitTestCase {
    *   The chain calculator.
    */
   protected function setUpChainCalculator(
-    VariationCacheInterface $variation_cache = NULL,
-    VariationCacheInterface $variation_cache_static = NULL,
-    CacheBackendInterface $cache_static = NULL,
-    AccountSwitcherInterface $account_switcher = NULL,
+    ?VariationCacheInterface $variation_cache = NULL,
+    ?VariationCacheInterface $variation_cache_static = NULL,
+    ?CacheBackendInterface $cache_static = NULL,
+    ?AccountSwitcherInterface $account_switcher = NULL,
   ) {
     if (!isset($variation_cache)) {
       $variation_cache = $this->prophesize(VariationCacheInterface::class);