diff --git a/tests/wpt/resources/testharnessreport.js b/tests/wpt/resources/testharnessreport.js
index c9817431..38a17de0 100644
--- a/tests/wpt/resources/testharnessreport.js
+++ b/tests/wpt/resources/testharnessreport.js
@@ -20,7 +20,7 @@ add_completion_callback(function (tests, status) {
     const test = tests[i];
     log += test.name+"|"+test.format_status();
     if (test.message != null) {
-      log +=  "|"+test.message;
+      log +=  "|"+test.message.replaceAll("\n"," ");
     }
     log += "\n";