diff --git a/src/lib.rs b/src/lib.rs
index 13e123f..da7e71a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,5 @@
 use rayon::prelude::*;
-use std::ops::{Add, Index, IndexMut, Neg};
+use std::ops::{Add, Index, IndexMut, Sub};
 
 pub enum ReadError {
     BadSymbol,
@@ -49,11 +49,11 @@ impl Add for Pos {
     }
 }
 
-impl Neg for Pos {
+impl Sub for Pos {
     type Output = Self;
 
-    fn neg(self) -> Self {
-        Self(-self.0, -self.1)
+    fn sub(self, other: Self) -> Self {
+        Self(self.0 - other.0, self.1 - other.1)
     }
 }
 
@@ -251,7 +251,7 @@ impl State {
         for i in dir {
             match self.lvl[pos + *i] {
                 Cell::Goal(false) | Cell::None => {
-                    let dpos = pos + -*i;
+                    let dpos = pos - *i;
 
                     match self.lvl[dpos] {
                         Cell::Goal(false) | Cell::None => mbc += 1,