diff --git a/tests/src/FunctionalJavascript/AttachmentTest.php b/tests/src/FunctionalJavascript/AttachmentTest.php
index b0843d53..600c4cb7 100644
--- a/tests/src/FunctionalJavascript/AttachmentTest.php
+++ b/tests/src/FunctionalJavascript/AttachmentTest.php
@@ -121,6 +121,7 @@ public function testSubmitWebform() {
 
     // Ensure all files are loaded on the form.
     foreach ($this->fileParams as $name => $file) {
+      $this->getSession()->wait(1000);
       $this->assertSession()->pageTextContains($file['name']);
     }