diff --git a/benches/brainfuck.rs b/benches/brainfuck.rs
index a84a131..66377f5 100644
--- a/benches/brainfuck.rs
+++ b/benches/brainfuck.rs
@@ -3,27 +3,17 @@ extern crate rustijvm;
 extern crate test;
 
 use std::fs::File;
-use std::rc::Rc;
-use std::sync::Mutex;
-use std::io::{Cursor, Seek, SeekFrom, Read};
+use std::sync::{Arc, Mutex};
+use std::io::Cursor;
 use test::Bencher;
 
-fn run_bfi(file: &str) -> String {
+fn run_bfi(file: &str) {
     let file = File::open(file).expect("Missing bf file");
-    let rc = Rc::new(Mutex::new(Cursor::new(Vec::new())));
+    let rc = Arc::new(Mutex::new(Cursor::new(Vec::new())));
     let mut machine = rustijvm::Machine::new_from_file("files/bonus/bfi.ijvm").unwrap();
-    machine.set_output(rc.clone());
+    machine.set_output(rc);
     machine.set_input(Box::new(file));
-
     machine.run().unwrap();
-
-    let mut out = rc.lock().unwrap();
-    let mut string = String::new();
-
-    out.seek(SeekFrom::Start(0)).unwrap();
-    out.read_to_string(&mut string).unwrap();
-
-    string
 }
 
 #[bench]
diff --git a/benches/recurse.rs b/benches/recurse.rs
new file mode 100644
index 0000000..1225115
--- /dev/null
+++ b/benches/recurse.rs
@@ -0,0 +1,35 @@
+#![feature(test)]
+extern crate rustijvm;
+extern crate test;
+
+use std::sync::{Arc, Mutex};
+use std::io::Cursor;
+use test::Bencher;
+
+fn run_calc(input: &'static str) {
+    let rc = Arc::new(Mutex::new(Cursor::new(Vec::new())));
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/SimpleCalc.ijvm").unwrap();
+    machine.set_output(rc);
+    machine.set_input(Box::new(input.as_bytes()));
+    machine.run().unwrap();
+}
+
+#[bench]
+fn factorial_2(b: &mut Bencher) {
+    b.iter(|| run_calc("2!?."));
+}
+
+#[bench]
+fn factorial_5(b: &mut Bencher) {
+    b.iter(|| run_calc("5!?."));
+}
+
+#[bench]
+fn factorial_7(b: &mut Bencher) {
+    b.iter(|| run_calc("7!?."));
+}
+
+#[bench]
+fn factorial_10(b: &mut Bencher) {
+    b.iter(|| run_calc("10!?."));
+}
diff --git a/tests/advanced5.rs b/tests/advanced5.rs
new file mode 100644
index 0000000..1dcc73a
--- /dev/null
+++ b/tests/advanced5.rs
@@ -0,0 +1,40 @@
+extern crate rustijvm;
+
+use std::sync::{Arc, Mutex};
+use std::io::{Cursor, Seek, SeekFrom, Read};
+
+fn run_calc(input: &'static str, expected: &str) {
+    let rc = Arc::new(Mutex::new(Cursor::new(Vec::new())));
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/SimpleCalc.ijvm").unwrap();
+    machine.set_input(Box::new(input.as_bytes()));
+    machine.set_output(rc.clone());
+    machine.run().unwrap();
+
+    let mut out = rc.lock().unwrap();
+    let mut output = String::new();
+
+    out.seek(SeekFrom::Start(0)).unwrap();
+    out.read_to_string(&mut output).unwrap();
+
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn advanced5_level1() {
+    run_calc("0 0 + ? .", "0\n");
+    run_calc("0 9 + ? .", "9\n");
+    run_calc("9 0 + ? .", "9\n");
+    run_calc("9 9 - ? .", "0\n");
+}
+
+#[test]
+fn advanced5_level2() {
+    run_calc("    5 4 -?.", "1\n");
+    run_calc("  8  8 8  - + ?.", "8\n");
+}
+
+#[test]
+fn advanced5_level3() {
+    run_calc("1 1 + 1 1 + 1 1 + 1 1 + 1 1 + +-++?.", "2\n");
+    run_calc("9 8 -9 7-9 6-9 5-9 4-9 3-9 2-9 1-9 0- -+-+-+-+?.", "1\n");
+}
diff --git a/tests/advanced6.rs b/tests/advanced6.rs
new file mode 100644
index 0000000..8e1426a
--- /dev/null
+++ b/tests/advanced6.rs
@@ -0,0 +1,35 @@
+extern crate rustijvm;
+
+use std::sync::{Arc, Mutex};
+use std::io::{Cursor, Seek, SeekFrom, Read};
+
+fn run_calc(input: &'static str, expected: &str) {
+    let rc = Arc::new(Mutex::new(Cursor::new(Vec::new())));
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/SimpleCalc.ijvm").unwrap();
+    machine.set_input(Box::new(input.as_bytes()));
+    machine.set_output(rc.clone());
+    machine.run().unwrap();
+
+    let mut out = rc.lock().unwrap();
+    let mut output = String::new();
+
+    out.seek(SeekFrom::Start(0)).unwrap();
+    out.read_to_string(&mut output).unwrap();
+
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn advanced6_recurse1() {
+    run_calc("2!?.", "2\n");
+}
+
+#[test]
+fn advanced6_recurse2() {
+    run_calc("7!?.", "5040\n");
+}
+
+#[test]
+fn advanced6_recurse3() {
+    run_calc("8!?.", "40320\n");
+}