diff --git a/modules/select2_bef/tests/src/FunctionalJavascript/Select2BefTests.php b/modules/select2_bef/tests/src/FunctionalJavascript/Select2BefTests.php
index ef432bd..f072604 100644
--- a/modules/select2_bef/tests/src/FunctionalJavascript/Select2BefTests.php
+++ b/modules/select2_bef/tests/src/FunctionalJavascript/Select2BefTests.php
@@ -48,7 +48,7 @@ class Select2BefTests extends Select2BoxesTestsBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $select2befTestUser = $this->createUser([
diff --git a/tests/src/FunctionalJavascript/Select2BoxesTests.php b/tests/src/FunctionalJavascript/Select2BoxesTests.php
index 52cf423..a1a2ab0 100644
--- a/tests/src/FunctionalJavascript/Select2BoxesTests.php
+++ b/tests/src/FunctionalJavascript/Select2BoxesTests.php
@@ -15,7 +15,7 @@ class Select2BoxesTests extends Select2BoxesTestsBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
     $this->drupalLogin($this->user);
   }
diff --git a/tests/src/FunctionalJavascript/Select2BoxesTestsBase.php b/tests/src/FunctionalJavascript/Select2BoxesTestsBase.php
index 0cefa0f..b511f88 100644
--- a/tests/src/FunctionalJavascript/Select2BoxesTestsBase.php
+++ b/tests/src/FunctionalJavascript/Select2BoxesTestsBase.php
@@ -57,7 +57,7 @@ abstract class Select2BoxesTestsBase extends WebDriverTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->user = $this->createUser([