diff -u b/scripts/run-tests.sh b/scripts/run-tests.sh
--- b/scripts/run-tests.sh
+++ b/scripts/run-tests.sh
@@ -719,7 +719,8 @@
     $message = strip_tags($result->message, '<a>');  // Jenkins encodes the output so don't use any tags.
     $message = preg_replace('/<a.*?href="([^"]+)".*?>(.*?)<\/a>/', '$1 $2', $message); // Jenkins will turn urls into clickable links.
     $message = $status . ' [' . $result->message_group . '] ' . $message . ' [' . basename($result->file) . ':' . $result->line . "]\n";
-    
+    $message = preg_replace('/[^\x{0009}\x{000A}\x{000D}\x{0020}-\x{D7FF}\x{E000}-\x{FFFD}\x{10000}-\x{10FFFF}]/u', '�', $message);
+
     // Everything else is logged in system_out.
     $test_case->system_out .= $message;
     // Failures go to failures.