diff --git a/exercises/quiz3.rs b/exercises/quiz3.rs
index a0cd3712..fae0eedb 100644
--- a/exercises/quiz3.rs
+++ b/exercises/quiz3.rs
@@ -24,6 +24,7 @@ mod tests {
 
     #[test]
     fn returns_twice_of_negative_numbers() {
-        // TODO write an assert for `times_two(-4)`
+        // TODO replace unimplemented!() with an assert for `times_two(-4)`
+        unimplemented!()
     }
 }