diff --git a/core/modules/layout_builder/tests/src/Functional/LayoutTaxonomyTest.php b/core/modules/layout_builder/tests/src/Functional/LayoutTaxonomyTest.php
index d7e19df84d..cd41ce0af7 100644
--- a/core/modules/layout_builder/tests/src/Functional/LayoutTaxonomyTest.php
+++ b/core/modules/layout_builder/tests/src/Functional/LayoutTaxonomyTest.php
@@ -30,6 +30,9 @@ class LayoutTaxonomyTest extends BrowserTestBase {
   public function testTaxonomyLayoutBuilderInteraction() {
     $assert_session = $this->assertSession();
 
+    // Prime the block definition cache.
+    $this->container->get('plugin.manager.block')->getDefinitions();
+
     $vocabulary = $this->createVocabulary();
     EntityViewDisplay::create([
       'targetEntityType' => 'taxonomy_term',