diff --git a/lib/index.js b/lib/index.js
index 7979544..88f1b3f 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -6,7 +6,7 @@ function retry(fn, opts) {
     var options = opts || {};
 
     // Default `randomize` to true
-    if (!'randomize' in opts) {
+    if (!('randomize' in opts)) {
       opts.randomize = true;
     }