diff --git a/src/lib.rs b/src/lib.rs
index a72a6e3..7beb228 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,4 @@
+#![feature(test)]
 #![allow(dead_code)]
 
 mod builtins;
diff --git a/src/vm/test.rs b/src/vm/test.rs
index 9f6eb64..f92bbb3 100644
--- a/src/vm/test.rs
+++ b/src/vm/test.rs
@@ -1,3 +1,7 @@
+extern crate test;
+
+use test::{Bencher, black_box};
+
 use ecow::EcoString;
 use rpds::{ht_map_sync, vector_sync};
 
@@ -189,3 +193,15 @@ fn test_func() {
         int!(3),
     );
 }
+
+#[test]
+#[ignore]
+fn test_fib() {
+    test_expr("let fib = n: if n == 1 || n == 2 then 1 else (fib (n - 1)) + (fib (n - 2)); in fib 30", int!(832040))
+}
+
+#[bench]
+#[ignore]
+fn bench_fib(b: &mut Bencher) {
+    b.iter(|| black_box(test_expr("let fib = n: if n == 1 || n == 2 then 1 else (fib (n - 1)) + (fib (n - 2)); in fib 20", int!(6765))))
+}