diff --git a/src/ResultPrinter/HTML.php b/src/ResultPrinter/HTML.php
index 7be5b29..1b0acb7 100644
--- a/src/ResultPrinter/HTML.php
+++ b/src/ResultPrinter/HTML.php
@@ -297,6 +297,9 @@ protected function renderSubsteps(Meta $metaStep, $substepsBuffer)
     private function cleanMessage($exception)
     {
         $msg = $exception->getMessage();
+        if ($exception instanceof \PHPUnit\Framework\AssertionFailedError && $exception->getComparisonFailure()) {
+            $msg .= $exception->getComparisonFailure()->getDiff();
+        }
         $msg = str_replace(['<info>','</info>','<bold>','</bold>'], ['','','',''], $msg);
         return htmlentities($msg);
     }