diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockViewBuilderTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockViewBuilderTest.php
index 2b72a90..31dffeb 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockViewBuilderTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockViewBuilderTest.php
@@ -198,7 +198,7 @@ public function testBlockViewBuilderAlter() {
     // Establish baseline.
     $build = $this->getBlockRenderArray();
     $this->assertIdentical(drupal_render($build), 'Llamas > unicorns!');
-
+    $build = $this->getBlockRenderArray();
     // Enable the block view alter hook that adds a suffix, for basic testing.
     \Drupal::state()->set('block_test_view_alter_suffix', TRUE);
 
diff --git a/core/modules/block/tests/modules/block_test/block_test.module b/core/modules/block/tests/modules/block_test/block_test.module
index a527ae1..d840cca 100644
--- a/core/modules/block/tests/modules/block_test/block_test.module
+++ b/core/modules/block/tests/modules/block_test/block_test.module
@@ -21,7 +21,7 @@ function block_test_block_alter(&$block_info) {
  */
 function block_test_block_view_test_cache_alter(array &$build, BlockPluginInterface $block) {
   if (\Drupal::state()->get('block_test_view_alter_suffix') !== NULL) {
-    $build['#suffix'] = '<br>Goodbye!';
+    $build['#suffix'] = '<br />Goodbye!';
   }
   if (\Drupal::state()->get('block_test_view_alter_cache_key') !== NULL) {
     $build['#cache']['keys'][] = \Drupal::state()->get('block_test_view_alter_cache_key');
@@ -38,6 +38,6 @@ function block_test_block_view_test_cache_alter(array &$build, BlockPluginInterf
  * #pre_render callback for a block to alter its content.
  */
 function block_test_pre_render_alter_content($build) {
-  $build['#prefix'] = 'Hiya!<br>';
+  $build['#prefix'] = 'Hiya!<br />';
   return $build;
 }