diff --git a/src/types/primitive/train_angle.rs b/src/types/primitive/train_angle.rs
index ff3d39e..82e7011 100644
--- a/src/types/primitive/train_angle.rs
+++ b/src/types/primitive/train_angle.rs
@@ -31,7 +31,88 @@ pub fn write(train_angle: &u16) -> BinResult<()> {
         return Err(Error::AssertFail { pos, message: ERR_MESSAGE_RANGE.to_string() });
     }
 
-    let raw = (*train_angle * 3) as u8;
+    let raw = (*train_angle / 3) as u8;
     raw.write(writer)?;
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use binrw::{io::Cursor, Endian};
+
+    use log::info;
+    use test_log::test;
+
+    #[test]
+    fn test_valid() {
+        let cases = vec![(0, true), (180, true), (360, true), (361, false)];
+
+        for (train_angle, want) in cases {
+            info!("Testing validity of {train_angle:?}, want {want:?}");
+            let got = valid(train_angle);
+            assert_eq!(want, got);
+        }
+    }
+
+    const BINARY_ENDIAN: Endian = Endian::Big;
+    const BINARY_CASES: [(u16, [u8; 1]); 4] = [
+        (0, [0]),   // 0° (0 * 3)
+        (3, [1]),   // 3° (1 * 3)
+        (180, [60]), // 180° (60 * 3)
+        (360, [120]), // 360° (120 * 3)
+    ];
+
+    #[test]
+    fn test_parse() {
+        for &(want, bytes) in BINARY_CASES.iter() {
+            info!("Parsing {bytes:?}, want {want:?}");
+            let mut cursor = Cursor::new(bytes);
+            let got = parse(&mut cursor, BINARY_ENDIAN, ()).expect("It should not return an error");
+            assert_eq!(want, got);
+        }
+    }
+
+    #[test]
+    fn test_parse_invalid() {
+        let cases = [
+            [0xC1], // 361° (out of range, 120 * 3 + 1)
+            [0xFF], // 765° (out of range, 255 * 3)
+        ];
+
+        for bytes in cases.iter() {
+            info!("Parsing {bytes:?}, want error");
+            let mut cursor = Cursor::new(bytes);
+            let error = parse(&mut cursor, BINARY_ENDIAN, ()).unwrap_err();
+            assert!(matches!(error, Error::AssertFail { .. }));
+        }
+    }
+
+    #[test]
+    fn test_write() {
+        for (train_angle, want) in BINARY_CASES.iter() {
+            info!("Writing {train_angle:?}, want {want:?}");
+            let mut cursor = Cursor::new(Vec::new());
+            write(&train_angle, &mut cursor, BINARY_ENDIAN, ())
+                .expect("It should not return an error");
+            let inner = cursor.into_inner();
+            let got = inner.as_slice();
+            assert_eq!(want, got);
+        }
+    }
+
+    #[test]
+    fn test_write_invalid() {
+        let cases = [
+            361, // Just over max
+            400, // Well over max
+        ];
+
+        for train_angle in cases.iter() {
+            info!("Writing {train_angle:?}, want error");
+            let mut cursor = Cursor::new(Vec::new());
+            let error = write(train_angle, &mut cursor, BINARY_ENDIAN, ()).unwrap_err();
+            assert!(matches!(error, Error::AssertFail { .. }));
+        }
+    }
+}