diff --git a/core/modules/block/lib/Drupal/block/Tests/Views/DisplayBlockTest.php b/core/modules/block/lib/Drupal/block/Tests/Views/DisplayBlockTest.php
index 463bcd5..3cb8462 100644
--- a/core/modules/block/lib/Drupal/block/Tests/Views/DisplayBlockTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/Views/DisplayBlockTest.php
@@ -94,8 +94,10 @@ public function testBlockCategory() {
 
     $this->drupalPostForm(NULL, array(), t('Save'));
 
+    // The category wiil have been sanitized, had any leading or trailing
+    // hyphens removed, and then converted to a unique HTML ID.
+    $category_id = 'edit-' . drupal_html_id(trim(String::checkPlain($category), '-'));
     // Test that the blocks are listed under the correct categories.
-    $category_id = 'edit-' . drupal_html_id(String::checkPlain($category));
     $arguments[':id'] = $category_id;
     $this->drupalGet('admin/structure/block');
     $elements = $this->xpath('//details[@id=:id]//li[contains(@class, :li_class)]/a[contains(@href, :href) and text()=:text]', $arguments);