diff --git a/src/moov.rs b/src/moov.rs
index 4a22fec..b79a55d 100644
--- a/src/moov.rs
+++ b/src/moov.rs
@@ -1,39 +1,44 @@
-use std::fmt;
-
 use super::piece::*;
 use super::square::*;
 use super::types::*;
+use std::fmt;
+use std::num::NonZeroU16;
 
-#[derive(Copy, Clone, Default, Debug, PartialEq, Eq)]
-pub struct Move(MoveInt);
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub struct Move(NonZeroU16);
 
 impl Move {
     pub fn new(from_sq: SQ, to_sq: SQ, flags: MoveFlags) -> Self {
-        Self(((flags as MoveInt) << 12) | ((from_sq as MoveInt) << 6) | (to_sq as MoveInt))
+        Self(
+            NonZeroU16::new(
+                (flags as MoveInt) << 12 | (from_sq as MoveInt) << 6 | (to_sq as MoveInt),
+            )
+            .expect("MoveInt is zero."),
+        )
     }
 
     pub fn to_sq(&self) -> SQ {
-        SQ::from((self.0 & 0x3f) as u8)
+        SQ::from((self.0.get() & 0x3f) as u8)
     }
 
     pub fn from_sq(&self) -> SQ {
-        SQ::from(((self.0 >> 6) & 0x3f) as u8)
+        SQ::from(((self.0.get() >> 6) & 0x3f) as u8)
     }
 
     pub fn flags(&self) -> MoveFlags {
-        MoveFlags::from(((self.0 >> 12) & 0xf) as u8)
+        MoveFlags::from(((self.0.get() >> 12) & 0xf) as u8)
     }
 
     pub fn move_int(&self) -> MoveInt {
-        self.0
+        self.0.get()
     }
 
     pub fn is_quiet(&self) -> bool {
-        (self.0 >> 12) & 0b1100 == 0
+        (self.0.get() >> 12) & 0b1100 == 0
     }
 
     pub fn is_capture(&self) -> bool {
-        (self.0 >> 12) & 0b0100 != 0
+        (self.0.get() >> 12) & 0b0100 != 0
     }
 
     pub fn is_ep(&self) -> bool {
@@ -57,7 +62,7 @@ impl Move {
 
 impl From<MoveInt> for Move {
     fn from(m: MoveInt) -> Self {
-        Self(m)
+        Self(NonZero::new(m).expect("MoveInt is zero."))
     }
 }
 
diff --git a/src/square.rs b/src/square.rs
index b8b4165..ef05346 100644
--- a/src/square.rs
+++ b/src/square.rs
@@ -26,7 +26,7 @@ impl SQ {
     }
 
     pub fn bb(self) -> Bitboard {
-        Self::SQUARES_BB[self as usize]
+        B!(1 << self as usize)
     }
 
     pub fn index(self) -> usize {
diff --git a/src/tt.rs b/src/tt.rs
index d7f83d7..a4767d3 100644
--- a/src/tt.rs
+++ b/src/tt.rs
@@ -14,7 +14,7 @@ use super::types::*;
 #[derive(Eq, PartialEq, Copy, Clone)]
 pub struct TTEntry {
     value: Value,
-    best_move: MoveInt,
+    best_move: Option<Move>,
     depth: Depth,
     flag: Bound,
 }
@@ -22,7 +22,7 @@ pub struct TTEntry {
 impl TTEntry {
     pub fn new(value: Value, best_move: Option<Move>, depth: Depth, flag: Bound) -> Self {
         TTEntry {
-            best_move: best_move.map_or(0, |m| m.move_int()),
+            best_move,
             depth,
             value,
             flag,
@@ -30,10 +30,7 @@ impl TTEntry {
     }
 
     pub fn best_move(&self) -> Option<Move> {
-        match self.best_move {
-            0 => None,
-            1.. => Some(Move::from(self.best_move)),
-        }
+        self.best_move
     }
 
     pub fn depth(&self) -> Depth {
@@ -52,7 +49,7 @@ impl TTEntry {
 impl Default for TTEntry {
     fn default() -> Self {
         Self {
-            best_move: 0,
+            best_move: None,
             depth: 0,
             value: 0,
             flag: Bound::Exact,
diff --git a/src/uci.rs b/src/uci.rs
index 4ba878a..9f9c7da 100644
--- a/src/uci.rs
+++ b/src/uci.rs
@@ -199,5 +199,5 @@ static PERFT_RE: LazyLock<Regex> = LazyLock::new(|| {
                 (?P<depth>.*?)
             $",
     )
-        .expect("Failed to compile perft regex.")
+    .expect("Failed to compile perft regex.")
 });