diff --git a/examples/chapter09/04-Fibonacci.js b/examples/chapter09/04-Fibonacci.js
index 3b395774..67eae205 100644
--- a/examples/chapter09/04-Fibonacci.js
+++ b/examples/chapter09/04-Fibonacci.js
@@ -30,7 +30,7 @@ function fibonacciMemoization(n) {
   const memo = [0, 1];
   const fibonacci = (n) => {
     if (memo[n] != null) return memo[n];
-    return memo[n] = fibonacci(n - 1, memo) + fibonacci(n - 2, memo);
+    return memo[n] = fibonacci(n - 1) + fibonacci(n - 2);
   };
   return fibonacci(n);
 }