diff --git a/core/src/coordinates.rs b/core/src/coordinates.rs
index f165a9a..b0c67ee 100644
--- a/core/src/coordinates.rs
+++ b/core/src/coordinates.rs
@@ -67,7 +67,14 @@ macro_rules! range_bound_struct {
                 }
             }
 
+            /// Create a new `Self`
+            ///
+            /// # Safety
+            ///
+            /// This function does not perform any bounds checking. It should only be called when
+            /// the input is already known to be within bounds, i.e. when `x >= Self::FIRST && x < Self::LAST`.
             $vis unsafe fn new_unchecked(x: $repr) -> Self {
+                debug_assert!((Self::FIRST.0..=Self::LAST.0).contains(&x));
                 Self(x)
             }
 
@@ -76,9 +83,9 @@ macro_rules! range_bound_struct {
             }
         }
 
-        impl Into<$repr> for $type {
-            fn into(self) -> $repr {
-                self.0
+        impl From<$type> for $repr {
+            fn from(x: $type) -> Self {
+                x.0
             }
         }
 
@@ -200,7 +207,11 @@ coordinate_enum!(Square, [
 ]);
 
 impl Square {
+    /// # Safety
+    ///
+    /// This function does not do any bounds checking on the input.
     pub unsafe fn from_index(x: u8) -> Square {
+        debug_assert!((x as usize) < Self::NUM);
         Self::try_from(x).unwrap_unchecked()
     }
 
@@ -233,50 +244,37 @@ impl Square {
         let index: u8 = self as u8;
         let dir: i8 = direction.to_offset();
         match direction {
-            Direction::North => Square::try_from(index.wrapping_add_signed(dir)).ok(),
+            Direction::North | Direction::NorthEast => {
+                Square::try_from(index.wrapping_add_signed(dir)).ok()
+            }
             Direction::NorthWest => {
-                if self.rank() != Rank::EIGHT {
-                    Square::try_from(index.wrapping_add_signed(dir)).ok()
-                } else {
+                if self.rank() == Rank::EIGHT {
                     None
+                } else {
+                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 }
             }
             Direction::West => {
-                if self.file() != File::A {
-                    Square::try_from(index.wrapping_add_signed(dir)).ok()
-                } else {
+                if self.file() == File::A {
                     None
+                } else {
+                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 }
             }
-            Direction::SouthWest => {
-                if self.rank() != Rank::ONE {
-                    Square::try_from(index.wrapping_add_signed(dir)).ok()
-                } else {
+            Direction::SouthEast | Direction::South | Direction::SouthWest => {
+                if self.rank() == Rank::ONE {
                     None
-                }
-            }
-            Direction::South => {
-                if self.rank() != Rank::ONE {
-                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 } else {
-                    None
-                }
-            }
-            Direction::SouthEast => {
-                if self.rank() != Rank::ONE {
                     Square::try_from(index.wrapping_add_signed(dir)).ok()
-                } else {
-                    None
                 }
             }
             Direction::East => {
-                if self.file() != File::H {
-                    Square::try_from(index.wrapping_add_signed(dir)).ok()
-                } else {
+                if self.file() == File::H {
                     None
+                } else {
+                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 }
             }
-            Direction::NorthEast => Square::try_from(index.wrapping_add_signed(dir)).ok(),
         }
     }
 }
@@ -300,7 +298,7 @@ impl FromStr for Square {
             .and_then(|c| c.try_into().ok())
             .ok_or(ParseSquareError)?;
 
-        if !chars.next().is_none() {
+        if chars.next().is_some() {
             return Err(ParseSquareError);
         }
 
@@ -328,17 +326,17 @@ impl fmt::Display for Square {
     }
 }
 
-impl Into<char> for File {
-    fn into(self) -> char {
-        let value: u8 = self.into();
-        (value + 'a' as u8) as char
+impl From<File> for char {
+    fn from(value: File) -> Self {
+        let u8value: u8 = value.into();
+        (u8value + b'a') as char
     }
 }
 
 impl Into<char> for Rank {
     fn into(self) -> char {
         let value: u8 = self.into();
-        (value + '1' as u8) as char
+        (value + b'1') as char
     }
 }
 
@@ -346,7 +344,7 @@ impl TryFrom<char> for File {
     type Error = ();
 
     fn try_from(value: char) -> Result<Self, Self::Error> {
-        File::try_from(value.to_ascii_lowercase() as u8 - 'a' as u8)
+        File::try_from(value.to_ascii_lowercase() as u8 - b'a')
     }
 }
 
@@ -354,7 +352,7 @@ impl TryFrom<char> for Rank {
     type Error = ();
 
     fn try_from(value: char) -> Result<Self, Self::Error> {
-        let result = (value as u8).checked_sub('1' as u8).ok_or(())?;
+        let result = (value as u8).checked_sub(b'1').ok_or(())?;
         Self::try_from(result)
     }
 }