diff --git a/lib/private/log-request.middleware.js b/lib/private/log-request.middleware.js
index 4875267..87fe8a0 100644
--- a/lib/private/log-request.middleware.js
+++ b/lib/private/log-request.middleware.js
@@ -51,8 +51,8 @@ module.exports = function logRequest(req, res, next) {
 
   // If `req._startTime` exists and is valid, then compute and include `middlewareLatency` in our report.
   // (Otherwise don't include middlewareLatency, since it'd be meaningless.)
-  if (_.isNumber(req._startTime)) {
-    report.diagnostic.middlewareLatency = receivedAt - req._startTime;
+  if (_.isNumber(req._startTime) || _.isDate(req._startTime)) {
+    report.diagnostic.middlewareLatency = receivedAt - req._startTime.valueOf();
   }//>-