diff --git a/src/ludus/interpreter.clj b/src/ludus/interpreter.clj
index 796e2e0..17b8eff 100644
--- a/src/ludus/interpreter.clj
+++ b/src/ludus/interpreter.clj
@@ -253,7 +253,7 @@
       (n) -> mult (n, fact (sub (n, 1)))
     }
 
-    fact (6)
+    fib (1)
 
 	")
 
@@ -278,6 +278,16 @@
 
 ")
 
+(defn fib [n]
+  (case n
+    0 1
+
+    1 1
+
+    (+ (fib (- n 1)) (fib (- n 2)))))
+
+(fib 35)
+