diff --git a/modules/simpletest/simpletest.css b/modules/simpletest/simpletest.css
index 8bd8944fbeb36a12b92c680db766267c32b78099..5cfedc68ccbab833421ec1e901ff6ee88c097cd4 100644
--- a/modules/simpletest/simpletest.css
+++ b/modules/simpletest/simpletest.css
@@ -59,6 +59,14 @@ tr.simpletest-exception.even {
   background: #f5e742;
 }
 
+tr.simpletest-debug.odd {
+  background: #eeeeee;
+}
+
+tr.simpletest-debug.even {
+  background: #ffffff;
+}
+
 div.simpletest-image {
   display: inline;
   cursor: pointer;
diff --git a/modules/simpletest/simpletest.pages.inc b/modules/simpletest/simpletest.pages.inc
index 1d208cf6e2293c9496ea23f0178c24e806a0975c..366fe91271e28e41e15333f0ff16b7ff60ef6450 100644
--- a/modules/simpletest/simpletest.pages.inc
+++ b/modules/simpletest/simpletest.pages.inc
@@ -254,7 +254,11 @@ function simpletest_result_form(&$form_state, $test_id) {
       $row[] = $assertion->function;
       $row[] = simpletest_result_status_image($assertion->status);
 
-      $rows[] = array('data' => $row, 'class' => 'simpletest-' . $assertion->status);
+      $class = 'simpletest-' . $assertion->status;
+      if ($assertion->message_group == 'Debug') {
+        $class = 'simpletest-debug';
+      }
+      $rows[] = array('data' => $row, 'class' => $class);
 
       $group_summary['#' . $assertion->status]++;
       $form['result']['summary']['#' . $assertion->status]++;