diff --git a/TODO b/TODO
index 4d28a40..8b60439 100644
--- a/TODO
+++ b/TODO
@@ -1,5 +1,6 @@
 # Bugs
 - Uninitialized variables don't compile
+- stdlib moves line of file, which makes error reporting impossible
 
 # Features 
 - For loop
diff --git a/examples/ackermann.sb b/examples/ackermann.sb
new file mode 100644
index 0000000..64ffc09
--- /dev/null
+++ b/examples/ackermann.sb
@@ -0,0 +1,15 @@
+fn main() {
+    let m = 3
+    let n = 3
+    println(ackermann(m, n))
+}
+
+fn ackermann(m, n) {
+    if m == 0 {
+        return n + 1
+    } else if n == 0 {
+        return ackermann(m - 1, 1)
+    } else {
+        return ackermann(m - 1, ackermann(m, n - 1))
+    }
+}
\ No newline at end of file
diff --git a/src/parser/rules.rs b/src/parser/rules.rs
index d968118..91042fc 100644
--- a/src/parser/rules.rs
+++ b/src/parser/rules.rs
@@ -79,6 +79,9 @@ impl Parser {
         while let Err(_) = self.peek_token(TokenKind::BraceClose) {
             let next = self.next()?;
             match next.kind {
+                TokenKind::Comma => {
+                    continue;
+                }
                 TokenKind::Identifier(name) => args.push(Variable { name: name }),
                 _ => return Err(self.make_error(TokenKind::Identifier("Argument".into()), next)),
             }
diff --git a/src/parser/tests.rs b/src/parser/tests.rs
index 1a95b62..255db51 100644
--- a/src/parser/tests.rs
+++ b/src/parser/tests.rs
@@ -530,3 +530,27 @@ fn test_uninitialized_variables() {
     let tree = parse(tokens, Some(raw.to_string()));
     assert!(tree.is_ok())
 }
+
+#[test]
+fn test_function_call_math() {
+    let raw = "
+    fn main(m) {
+        main(m - 1)
+    }
+    ";
+    let tokens = tokenize(raw);
+    let tree = parse(tokens, Some(raw.to_string()));
+    assert!(tree.is_ok())
+}
+
+#[test]
+fn test_function_multiple_args() {
+    let raw = "
+    fn main(m, n) {
+        main(m, n)
+    }
+    ";
+    let tokens = tokenize(raw);
+    let tree = parse(tokens, Some(raw.to_string()));
+    assert!(tree.is_ok())
+}