diff --git a/thunk_test.go b/thunk_test.go
index bd7aaec..b8b274f 100644
--- a/thunk_test.go
+++ b/thunk_test.go
@@ -15,6 +15,24 @@ func TestRecurFib(t *testing.T) {
 	t.Log(Fib(40))
 }
 
+func TestMemoizedFib(t *testing.T) {
+	mem := map[int]int{
+		0: 0,
+		1: 1,
+	}
+
+	var fib func(int) int
+	fib = func(n int) int {
+		if result, ok := mem[n]; ok {
+			return result
+		}
+
+		result := fib(n-1) + fib(n-2)
+		mem[n] = result
+		return result
+	}
+}
+
 func TestThunkFib(t *testing.T) {
 	cache := make([]*Thunk[int], 41)