diff --git a/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonAnonTest.php b/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonAnonTest.php
index 3e5076d333..b1acad5904 100644
--- a/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonAnonTest.php
+++ b/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonAnonTest.php
@@ -26,4 +26,9 @@ class WorkspaceHalJsonAnonTest extends WorkspaceHalJsonTestBase {
    */
   protected static $mimeType = 'application/hal+json';
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
 }
diff --git a/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonBasicAuthTest.php b/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonBasicAuthTest.php
index 45e059b615..8f6ab7719b 100644
--- a/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonBasicAuthTest.php
+++ b/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonBasicAuthTest.php
@@ -31,4 +31,9 @@ class WorkspaceHalJsonBasicAuthTest extends WorkspaceHalJsonTestBase {
    */
   protected static $auth = 'basic_auth';
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
 }
diff --git a/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonCookieTest.php b/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonCookieTest.php
index f8ac9401e7..15bd0e6797 100644
--- a/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonCookieTest.php
+++ b/core/modules/workspaces/tests/src/Functional/Hal/WorkspaceHalJsonCookieTest.php
@@ -31,4 +31,9 @@ class WorkspaceHalJsonCookieTest extends WorkspaceHalJsonTestBase {
    */
   protected static $auth = 'cookie';
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $defaultTheme = 'stark';
+
 }