diff --git a/modules/search_api_db/tests/src/FunctionalJavascript/IntegrationTest.php b/modules/search_api_db/tests/src/FunctionalJavascript/IntegrationTest.php
index 8e2046c2..f3606107 100644
--- a/modules/search_api_db/tests/src/FunctionalJavascript/IntegrationTest.php
+++ b/modules/search_api_db/tests/src/FunctionalJavascript/IntegrationTest.php
@@ -19,6 +19,13 @@ class IntegrationTest extends WebDriverTestBase {
     'search_api_db',
   ];
 
+  /**
+   * The theme to install as the default for testing.
+   *
+   * @var string
+   */
+  protected $defaultTheme = 'stark';
+
   /**
    * Tests that adding a server works.
    */
diff --git a/tests/src/Functional/AddServerFormTest.php b/tests/src/Functional/AddServerFormTest.php
index 977c45f5..cf221d3e 100644
--- a/tests/src/Functional/AddServerFormTest.php
+++ b/tests/src/Functional/AddServerFormTest.php
@@ -20,6 +20,13 @@ class AddServerFormTest extends BrowserTestBase {
     'search_api',
   ];
 
+  /**
+   * The theme to install as the default for testing.
+   *
+   * @var string
+   */
+  protected $defaultTheme = 'stark';
+
   /**
    * {@inheritdoc}
    */