diff --git a/src/board.rs b/src/board.rs
index 5edaed9..a24ffa8 100644
--- a/src/board.rs
+++ b/src/board.rs
@@ -213,7 +213,7 @@ impl Rank {
 
     #[inline]
     pub fn mirror(self) -> Self {
-        unsafe { Self::new_unchecked(7_u8.unchecked_sub(self as u8)) }
+        unsafe { Self::new_unchecked(!(self as u8)) }
     }
 
     #[inline]
@@ -305,7 +305,8 @@ impl Square {
 
     #[inline]
     pub fn mirror(self) -> Self {
-        Self::from_coords(self.file(), self.rank().mirror())
+        let sq = self as u8;
+        unsafe { Self::new_unchecked(sq & 0b000111 | (!sq & 0b111000)) }
     }
 
     #[inline]