diff --git a/lib/support/flattenMessage.js b/lib/support/flattenMessage.js
index cb4da22c0d..5a003be243 100644
--- a/lib/support/flattenMessage.js
+++ b/lib/support/flattenMessage.js
@@ -45,6 +45,13 @@ module.exports = {
       if (keyPrefix.match(/(screenshots\.|har\.)/)) {
           return;
       }
+
+      // Google is overloading User Timing marks
+      // See https://github.com/sitespeedio/browsertime/issues/257
+      if (keyPrefix.indexOf('userTimings.marks.goog_') > -1) {
+        return;
+      }
+
       const valueType = typeof value;
 
       switch (valueType) {