diff --git a/exercises/functions/functions3.rs b/exercises/functions/functions3.rs
index e3c1bf7..ed5f839 100644
--- a/exercises/functions/functions3.rs
+++ b/exercises/functions/functions3.rs
@@ -7,7 +7,7 @@ fn main() {
     call_me();
 }
 
-fn call_me(num: i32) {
+fn call_me(num: u32) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }