diff --git a/exercises/practice/armstrong-numbers/.meta/example.rs b/exercises/practice/armstrong-numbers/.meta/example.rs
index baa37f282..a14413c63 100644
--- a/exercises/practice/armstrong-numbers/.meta/example.rs
+++ b/exercises/practice/armstrong-numbers/.meta/example.rs
@@ -3,6 +3,6 @@ pub fn is_armstrong_number(num: u32) -> bool {
     let l = s.len();
     s.chars()
         .map(|c| c.to_digit(10).unwrap().pow(l as u32))
-        .sum::<u32>()
-        == num
+        .try_fold(0u32, u32::checked_add)
+        == Some(num)
 }
diff --git a/exercises/practice/armstrong-numbers/tests/armstrong-numbers.rs b/exercises/practice/armstrong-numbers/tests/armstrong-numbers.rs
index 2163451f1..8e5713b05 100644
--- a/exercises/practice/armstrong-numbers/tests/armstrong-numbers.rs
+++ b/exercises/practice/armstrong-numbers/tests/armstrong-numbers.rs
@@ -52,3 +52,30 @@ fn test_seven_digit_armstrong_number() {
 fn test_seven_digit_non_armstrong_number() {
     assert!(!is_armstrong_number(9_926_316))
 }
+
+#[test]
+#[ignore]
+fn test_nine_digit_armstrong_number() {
+    assert!(is_armstrong_number(912_985_153));
+}
+
+#[test]
+#[ignore]
+fn test_nine_digit_non_armstrong_number() {
+    assert!(!is_armstrong_number(999_999_999));
+}
+
+#[test]
+#[ignore]
+fn test_ten_digit_non_armstrong_number() {
+    assert!(!is_armstrong_number(3_999_999_999));
+}
+
+// The following number has an Armstrong sum equal to 2^32 plus itself,
+// and therefore will be detected as an Armstrong number if you are
+// incorrectly using wrapping arithmetic.
+#[test]
+#[ignore]
+fn test_properly_handles_overflow() {
+    assert!(!is_armstrong_number(4_106_098_957));
+}