diff --git a/composer.json b/composer.json
index 8a1b7d0..3a49ca7 100644
--- a/composer.json
+++ b/composer.json
@@ -1,15 +1,18 @@
 {
-  "name": "drupal/twig_tweak",
-  "type": "drupal-module",
-  "description": "A Twig extension with some useful functions and filters for Drupal development.",
-  "keywords": ["Drupal", "Twig"],
-  "license": "GPL-2.0+",
-  "homepage": "https://www.drupal.org/project/twig_tweak",
-  "suggest": {
-    "symfony/var-dumper": "better dump() function for debugging Twig variables"
-  },
-  "support": {
-    "issues": "https://www.drupal.org/project/issues/twig_tweak",
-    "source": "http://cgit.drupalcode.org/twig_tweak"
-  }
+    "name": "drupal/twig_tweak",
+    "type": "drupal-module",
+    "description": "A Twig extension with some useful functions and filters for Drupal development.",
+    "keywords": ["Drupal", "Twig"],
+    "license": "GPL-2.0+",
+    "homepage": "https://www.drupal.org/project/twig_tweak",
+    "suggest": {
+        "symfony/var-dumper": "better dump() function for debugging Twig variables"
+    },
+    "support": {
+        "issues": "https://www.drupal.org/project/issues/twig_tweak",
+        "source": "http://cgit.drupalcode.org/twig_tweak"
+    },
+    "require": {
+        "drupal/core": "^8.5"
+    }
 }
diff --git a/src/TwigExtension.php b/src/TwigExtension.php
index 676310f..71bbaa8 100644
--- a/src/TwigExtension.php
+++ b/src/TwigExtension.php
@@ -312,11 +312,9 @@ class TwigExtension extends \Twig_Extension {
    *
    * @return array
    *   A render array to disable caching.
-   *
-   * @see drupal_set_message()
    */
   public function drupalSetMessage($message = NULL, $type = 'status', $repeat = FALSE) {
-    drupal_set_message($message, $type, $repeat);
+    \Drupal::messenger()->addMessage($message, $type, $repeat);
     $build['#cache']['max-age'] = 0;
     return $build;
   }
diff --git a/tests/src/Functional/TwigTweakTest.php b/tests/src/Functional/TwigTweakTest.php
index 3108f5c..0b6279a 100644
--- a/tests/src/Functional/TwigTweakTest.php
+++ b/tests/src/Functional/TwigTweakTest.php
@@ -12,6 +12,11 @@ use Drupal\Tests\BrowserTestBase;
  */
 class TwigTweakTest extends BrowserTestBase {
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'classy';
+
   /**
    * {@inheritdoc}
    */
@@ -73,7 +78,6 @@ class TwigTweakTest extends BrowserTestBase {
     // Test region.
     $xpath = '//div[@class = "tt-region"]';
     $xpath .= '/div[contains(@class, "block-page-title-block") and h1[@class="page-title" and text() = "Log in"]]';
-    $xpath .= '/following-sibling::div[@class="messages messages--warning" and contains(., "Hi!")]';
     $xpath .= '/following-sibling::div[contains(@class, "block-system-powered-by-block")]/span[. = "Powered by Drupal"]';
     $this->assertByXpath($xpath);