diff --git a/admin/tool/unittest/ex_reporter.php b/admin/tool/unittest/ex_reporter.php
index 995bebd82ca30..5d440f37d6d46 100644
--- a/admin/tool/unittest/ex_reporter.php
+++ b/admin/tool/unittest/ex_reporter.php
@@ -289,4 +289,9 @@ function _stripParameterFromUrl($url, $param) {
     function get_string($identifier, $a = NULL) {
         return get_string($identifier, 'tool_unittest', $a);
     }
+
+    function _htmlEntities($message) {
+        // Override subclass message that breaks UTF8.
+        return s($message);
+    }
 }