diff --git a/solutions/18_iterators/iterators3.rs b/solutions/18_iterators/iterators3.rs
index 11aa1ec8..1d5d67f2 100644
--- a/solutions/18_iterators/iterators3.rs
+++ b/solutions/18_iterators/iterators3.rs
@@ -52,6 +52,8 @@ mod tests {
     #[test]
     fn test_success() {
         assert_eq!(divide(81, 9), Ok(9));
+        assert_eq!(divide(81, -1), Ok(-81));
+        assert_eq!(divide(i64::MIN, i64::MIN), Ok(1));
     }
 
     #[test]