diff --git a/src/EventSubscriber/CsvSubscriber.php b/src/EventSubscriber/CsvSubscriber.php
index e1bb763..e0d1cd4 100644
--- a/src/EventSubscriber/CsvSubscriber.php
+++ b/src/EventSubscriber/CsvSubscriber.php
@@ -24,7 +24,7 @@ class CsvSubscriber implements EventSubscriberInterface {
   /**
    * Implements \Symfony\Component\EventDispatcher\EventSubscriberInterface::getSubscribedEvents().
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     $events[KernelEvents::REQUEST][] = ['onKernelRequest'];
     return $events;
   }
diff --git a/tests/src/Unit/CsvEncoderTest.php b/tests/src/Unit/CsvEncoderTest.php
index 5319207..b78def6 100644
--- a/tests/src/Unit/CsvEncoderTest.php
+++ b/tests/src/Unit/CsvEncoderTest.php
@@ -33,7 +33,7 @@ class CsvEncoderTest extends UnitTestCase {
    * @return array
    *   Am array of multi-dimensional arrays, to be converted to CSVs.
    */
-  public function provideEncodeData() {
+  public static function provideEncodeData() {
     $csv1_data = [
       // Row 1.
       [
@@ -81,7 +81,7 @@ class CsvEncoderTest extends UnitTestCase {
   /**
    * Provides data for testing the decoder.
    */
-  public function provideDecodeData() {
+  public static function provideDecodeData() {
     $csv1_data = [
       // Row 0. - (Headers)
       [