diff --git a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php b/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
index cf74223fbd..5d873388b5 100644
--- a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
+++ b/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
@@ -116,6 +116,7 @@ public function testBlocks($block_plugin, $new_page_text, $element_selector, $la
         // Make sure the changes are present.
         $new_page_text_locator = "$block_selector $label_selector:contains($new_page_text)";
         $this->assertElementVisibleAfterWait('css', $new_page_text_locator);
+        $web_assert->assertWaitOnAjaxRequest();
       }
 
       $this->openBlockForm($block_selector);