diff --git a/src/lib.rs b/src/lib.rs
index b12e235..7dbd711 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -350,7 +350,6 @@ impl Agent {
     const BOX_DIFF: f32 = 1024.0;
 
     const DIR_TABLE: &'static [u32] = &[0, 1, 2, 3];
-    const DIR_STR: &[&str] = &["U", "D", "L", "R"];
 
     fn chromo() -> u32 {
         Self::DIR_TABLE[rnd!(Self::DIR_TABLE.len())]
@@ -458,7 +457,7 @@ impl Agent {
 
     fn solution(&self) -> String {
         (0..self.dir)
-            .map(|i| Self::DIR_STR[self.dna[i] as usize])
+            .map(|i| ["U", "D", "L", "R"][self.dna[i] as usize])
             .collect()
     }
 }