diff --git a/lib/bunyan.js b/lib/bunyan.js
index 6ed9e8a..7dfc385 100644
--- a/lib/bunyan.js
+++ b/lib/bunyan.js
@@ -1197,7 +1197,7 @@ function safeCyclesArray() {
  * Choose the best safe cycle function from what is available - see
  * trentm/node-bunyan#445.
  */
-var safeCycles = Set ? safeCyclesSet : safeCyclesArray;
+var safeCycles = typeof Set !== 'undefined' ? safeCyclesSet : safeCyclesArray;
 
 /**
  * A fast JSON.stringify that handles cycles and getter exceptions (when