diff --git a/src/bin/day12.rs b/src/bin/day12.rs
index b85d5b9..868221f 100644
--- a/src/bin/day12.rs
+++ b/src/bin/day12.rs
@@ -57,7 +57,7 @@ fn get_elevation(c: char) -> i32 {
     }
 }
 
-fn bfs<F, G>(graph: &Vec<Vec<char>>, start: &Position, has_edge: F, is_target: G) -> Option<usize>
+fn bfs<F, G>(graph: &[Vec<char>], start: &Position, has_edge: F, is_target: G) -> Option<usize>
 where
     F: Fn(&[Vec<char>], &Position, &Position) -> bool,
     G: Fn(&[Vec<char>], &Position) -> bool,