diff --git a/README.md b/README.md
index 755cbd0..118b492 100644
--- a/README.md
+++ b/README.md
@@ -281,6 +281,8 @@ expect(result).toEqual([1, 2, 3]);
 ```
 
 ```js
+function increment(x) { return x + 1; }
+
 var result = u.map(increment, { a: 0, b: 1, c: 2 });
 
 expect(result).toEqual({ a: 1, b: 2, c: 3 });