diff --git a/lib/utils.js b/lib/utils.js
index da7e0636..0796cd09 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -326,9 +326,19 @@ function prettifyObject ({
  * string.
  */
 function prettifyTime ({ log, timestampKey = TIMESTAMP_KEY, translateFormat = undefined }) {
-  if (timestampKey in log === false && 'timestamp' in log === false) return undefined
+  let time = null
+
+  if (timestampKey in log) {
+    time = log[timestampKey]
+  }
+  else if ('timestamp' in log) {
+    time = log.timestamp
+  }
+
+  if (time === null) return undefined
   if (translateFormat) {
-    return '[' + formatTime(log[timestampKey] || log.timestamp, translateFormat) + ']'
+    return '[' + formatTime(time, translateFormat) + ']'
   }
-  return `[${log[timestampKey] || log.timestamp}]`
+
+  return `[${log}]`
 }