diff --git a/src/diff/solver.rs b/src/diff/solver.rs
index 84ae0e9..7b59191 100644
--- a/src/diff/solver.rs
+++ b/src/diff/solver.rs
@@ -380,7 +380,7 @@ impl NoiseModel {
             NoiseModelState::new(n + 1),
             NoiseModelState::new(n + 1),
         ];
-        let mut coords = Vec::new();
+        let mut coords = Vec::with_capacity(n);
 
         let neg_lag = -(NOISE_MODEL_LAG as isize);
         for y in neg_lag..=0 {