diff --git a/test/fib.zrl b/test/fib.zrl
index 9f37ba1..04b9114 100644
--- a/test/fib.zrl
+++ b/test/fib.zrl
@@ -1,4 +1,4 @@
-fn fib(int n) {
+fn fib(i32 n) i32 {
   if (n < 2) return n;
   return fib(n - 2) + fib(n - 1);
 }