diff --git a/lib/_tls_wrap.js b/lib/_tls_wrap.js
index 4d98f3fa991e1e..0c3c0e3cfcbf7b 100644
--- a/lib/_tls_wrap.js
+++ b/lib/_tls_wrap.js
@@ -65,7 +65,8 @@ function onhandshakestart(now) {
   debug('onhandshakestart');
 
   const { lastHandshakeTime } = this;
-  assert(now >= lastHandshakeTime);
+  assert(now >= lastHandshakeTime,
+         `now (${now}) < lastHandshakeTime (${lastHandshakeTime})`);
 
   this.lastHandshakeTime = now;