diff --git a/rust/src/primes.rs b/rust/src/primes.rs
index d41a277c..f67f44c4 100644
--- a/rust/src/primes.rs
+++ b/rust/src/primes.rs
@@ -40,7 +40,7 @@ impl Iterator for Eratosthenes {
         fn next_prime(sieve: &mut HashMap<u64, Vec<u64>>, candidate: u64) -> u64 {
             match sieve.get(&candidate) {
                 Some(numbers) => {
-                    for num in numbers {
+                    for num in numbers.to_owned() {
                         sieve
                             .entry(candidate + num)
                             .and_modify(|v| v.push(num))