diff --git a/aoc_2024/src/day21.rs b/aoc_2024/src/day21.rs
index 4c21e16..167347a 100644
--- a/aoc_2024/src/day21.rs
+++ b/aoc_2024/src/day21.rs
@@ -131,11 +131,9 @@ impl NumButton {
     }
 }
 
-type Input = String;
-
 #[aoc_generator(day21)]
-fn parse(input: &str) -> Input {
-    input.to_string()
+fn parse(input: &str) -> &'static str {
+    unsafe { std::mem::transmute(input) }
 }
 
 type Path = [DistanceSize; 6];
@@ -336,7 +334,7 @@ const CHAR_IDX: [usize; 10] = [
 ];
 
 #[aoc(day21, part1)]
-fn part1(input: &Input) -> DistanceSize {
+fn part1(input: &str) -> DistanceSize {
     let num_paths = const {
         let steps = precompute_steps_new::<2>([[1; 5]; 5]);
         let paths = precompute_paths();
@@ -358,7 +356,7 @@ fn part1(input: &Input) -> DistanceSize {
 }
 
 #[aoc(day21, part2)]
-fn part2(input: &Input) -> DistanceSize {
+fn part2(input: &str) -> DistanceSize {
     let num_paths = const {
         let steps = precompute_steps_new::<25>([[1; 5]; 5]);
         let paths = precompute_paths();
@@ -385,10 +383,10 @@ mod tests {
 
     #[test]
     fn part1_example() {
-        assert_eq!(part1(&parse("379A")), 64 * 379);
-        assert_eq!(part1(&parse("179A")), 68 * 179);
-        assert_eq!(part1(&parse("456A")), 64 * 456);
-        assert_eq!(part1(&parse("980A")), 60 * 980);
-        assert_eq!(part1(&parse("029A")), 68 * 29);
+        assert_eq!(part1(parse("379A")), 64 * 379);
+        assert_eq!(part1(parse("179A")), 68 * 179);
+        assert_eq!(part1(parse("456A")), 64 * 456);
+        assert_eq!(part1(parse("980A")), 60 * 980);
+        assert_eq!(part1(parse("029A")), 68 * 29);
     }
 }