diff --git a/tests/src/Functional/FillPdfFormDeleteFormTest.php b/tests/src/Functional/FillPdfFormDeleteFormTest.php
index 4512237e97b97cae99f4dd43cbcbf17b5cabc0b3..bf43fe88aef60189e6f680c433acdd949463563b 100644
--- a/tests/src/Functional/FillPdfFormDeleteFormTest.php
+++ b/tests/src/Functional/FillPdfFormDeleteFormTest.php
@@ -29,7 +29,7 @@ class FillPdfFormDeleteFormTest extends BrowserTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->configureFillPdf();
diff --git a/tests/src/Functional/FillPdfFormDuplicateFormTest.php b/tests/src/Functional/FillPdfFormDuplicateFormTest.php
index b78a000b0bbf95419ea4a09a8a333733bff503de..9d072f9dbdc75f44919d32aa0464d2e6abca600a 100644
--- a/tests/src/Functional/FillPdfFormDuplicateFormTest.php
+++ b/tests/src/Functional/FillPdfFormDuplicateFormTest.php
@@ -29,7 +29,7 @@ class FillPdfFormDuplicateFormTest extends BrowserTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->configureFillPdf();
diff --git a/tests/src/Functional/FillPdfFormFormTest.php b/tests/src/Functional/FillPdfFormFormTest.php
index 098a3873921849e0f0f45655d6db11eeada918c8..612ba2aa00bb659300d79c6ddb44750174e54b3f 100644
--- a/tests/src/Functional/FillPdfFormFormTest.php
+++ b/tests/src/Functional/FillPdfFormFormTest.php
@@ -16,7 +16,7 @@ class FillPdfFormFormTest extends FillPdfUploadTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->testNode = $this->createNode([
diff --git a/tests/src/Functional/FillPdfFormImportFormTest.php b/tests/src/Functional/FillPdfFormImportFormTest.php
index 2d25e9998d67bfba306bd9bb852745670cb8fab6..ed7db6902556454976667c827c378583c6195120 100644
--- a/tests/src/Functional/FillPdfFormImportFormTest.php
+++ b/tests/src/Functional/FillPdfFormImportFormTest.php
@@ -27,7 +27,7 @@ class FillPdfFormImportFormTest extends BrowserTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->configureFillPdf();
diff --git a/tests/src/Functional/FillPdfSettingsFormTest.php b/tests/src/Functional/FillPdfSettingsFormTest.php
index 02cf2f7f9833ddadb379e6e45a78a0b9d9967e87..c21f77f0603466b7250b8e126b9f9a41fb614a10 100644
--- a/tests/src/Functional/FillPdfSettingsFormTest.php
+++ b/tests/src/Functional/FillPdfSettingsFormTest.php
@@ -35,7 +35,7 @@ class FillPdfSettingsFormTest extends BrowserTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->initializeUser();
diff --git a/tests/src/Functional/FillPdfTestBase.php b/tests/src/Functional/FillPdfTestBase.php
index a514406a408f1f2683c19266249235c633063f55..f70081e046afea43ab9a7bcc3fe9570ebfca71fe 100644
--- a/tests/src/Functional/FillPdfTestBase.php
+++ b/tests/src/Functional/FillPdfTestBase.php
@@ -94,7 +94,7 @@ abstract class FillPdfTestBase extends FileFieldTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     // Grant additional permissions to the logged-in admin user.
diff --git a/tests/src/Functional/HandlePdfControllerTest.php b/tests/src/Functional/HandlePdfControllerTest.php
index c8ad8720b2384cdf3cb69384d65f1224eadead0e..52080509d1d94b125e96390ffb69be8cb148cfef 100644
--- a/tests/src/Functional/HandlePdfControllerTest.php
+++ b/tests/src/Functional/HandlePdfControllerTest.php
@@ -21,7 +21,7 @@ class HandlePdfControllerTest extends FillPdfUploadTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->testNodes[1] = $this->createNode([
diff --git a/tests/src/Functional/LinkManipulatorTest.php b/tests/src/Functional/LinkManipulatorTest.php
index 62b8483ae162ad3d99087d7b7737b8cfd887bda4..bf36b460eabe45eda4b566938e307a10656f50e8 100644
--- a/tests/src/Functional/LinkManipulatorTest.php
+++ b/tests/src/Functional/LinkManipulatorTest.php
@@ -37,7 +37,7 @@ class LinkManipulatorTest extends BrowserTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->configureFillPdf();
diff --git a/tests/src/Functional/PdfPopulationTest.php b/tests/src/Functional/PdfPopulationTest.php
index 82cb207fcc4cd881841e441fbddaa1741597b044..0808aa08b2746569db4199e2137eadf1eb7bba71 100644
--- a/tests/src/Functional/PdfPopulationTest.php
+++ b/tests/src/Functional/PdfPopulationTest.php
@@ -49,7 +49,7 @@ class PdfPopulationTest extends FillPdfTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     // Grant additional permissions to the logged-in admin user.
diff --git a/tests/src/Functional/PdfWebformPopulationTest.php b/tests/src/Functional/PdfWebformPopulationTest.php
index 7ea9b64e78cffc3b8e74945511471699b1364dc7..580e0ac35f2cef90099c5f5661808d9cd7fde5cd 100644
--- a/tests/src/Functional/PdfWebformPopulationTest.php
+++ b/tests/src/Functional/PdfWebformPopulationTest.php
@@ -42,7 +42,7 @@ class PdfWebformPopulationTest extends FillPdfTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     // @todo: Stop skipping this test when Webform has Drupal 9 support.
     if (version_compare(substr(\Drupal::VERSION, 0, 1), 9, '>=')) {
       $this->markTestSkipped('Webform is not yet compatible with Drupal 9, so skipping these tests.');
diff --git a/tests/src/Functional/UninstallTest.php b/tests/src/Functional/UninstallTest.php
index 3df44c94b417a6b6cce605a3e425378e060f7a27..f7b7e6c080ad5fbc81bcef5a7edc0982e6f379f8 100644
--- a/tests/src/Functional/UninstallTest.php
+++ b/tests/src/Functional/UninstallTest.php
@@ -35,7 +35,7 @@ class UninstallTest extends BrowserTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->configureFillPdf();
diff --git a/tests/src/Kernel/FillPdfKernelTestBase.php b/tests/src/Kernel/FillPdfKernelTestBase.php
index f2b2b3ad35482e743de824563aca52d351ee1b90..74303557c242b26f6465db81dc856dd7f5a435fc 100644
--- a/tests/src/Kernel/FillPdfKernelTestBase.php
+++ b/tests/src/Kernel/FillPdfKernelTestBase.php
@@ -29,7 +29,7 @@ abstract class FillPdfKernelTestBase extends EntityKernelTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->installEntitySchema('fillpdf_form');