diff --git a/tests/src/Kernel/TaxonomyUniqueTest.php b/tests/src/Kernel/TaxonomyUniqueTest.php
index 02f557c..354604d 100644
--- a/tests/src/Kernel/TaxonomyUniqueTest.php
+++ b/tests/src/Kernel/TaxonomyUniqueTest.php
@@ -27,7 +27,7 @@ class TaxonomyUniqueTest extends KernelTestBase {
   /**
    * {@inheritdoc}
    */
-  public function setUp() {
+  public function setUp(): void {
     parent::setUp();
     $this->installConfig(['filter']);
     $this->installEntitySchema('taxonomy_term');