diff --git a/src/bin/p03.rs b/src/bin/p03.rs
index 8064db2..e6b647a 100644
--- a/src/bin/p03.rs
+++ b/src/bin/p03.rs
@@ -1,4 +1,4 @@
-#![feature(iterator_try_collect)]
+#![feature(iterator_try_collect, iter_collect_into)]
 
 use std::collections::HashSet;
 use std::fs;
@@ -32,10 +32,11 @@ fn to_priority(c: char) -> Result<u32, &'static str> {
 
 fn part1(lines: &[String]) {
     let mut sum: u32 = 0;
+    let mut left_set = HashSet::<char>::new();
+    let mut right_set = HashSet::<char>::new();
     for line in lines {
         let (left, right) = line.split_at(line.len() / 2);
-        let left_set: HashSet<char> = left.chars().collect();
-        let mut right_set = HashSet::<char>::new();
+        left.chars().collect_into(&mut left_set);
         let outlier = right
             .chars()
             .find(|c| {
@@ -47,6 +48,9 @@ fn part1(lines: &[String]) {
         let priority = to_priority(outlier).unwrap();
         println!("{} ({})", outlier, priority);
         sum += priority;
+
+        left_set.clear();
+        right_set.clear();
     }
 
     println!("Sum: {}", sum);