diff --git a/src/main.rs b/src/main.rs
index 392b93a..485a41f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,28 +1,64 @@
 use std::env::args;
 use std::net::UdpSocket;
 
-fn get_magic_pkt(mac: &String) -> [u8; 102] {
+fn get_magic_pkt(mac: &str, magic_bytes: &mut [u8; 102]) {
     let mut mac_bytes = [0u8; 6];
-    let mut magic_bytes = [0u8; 102];
-    magic_bytes[..6].fill(0xFF);
-
     for (i, part) in mac.split(':').enumerate() {
-        mac_bytes[i] = u8::from_str_radix(part, 16).unwrap();
+        mac_bytes[i] = u8::from_str_radix(part, 16)
+            .expect(&format!("'{}' is not a valid hex between 00-ff", part));
     }
+
+    magic_bytes[..6].fill(0xFF);
     for i in 0..16 {
         let start = 6 + i * 6;
         magic_bytes[start..start + 6].copy_from_slice(&mac_bytes);
     }
-    
-    magic_bytes
 }
 
 fn main() {
-    let mac = args().nth(1).expect("no mac given; Usage woly aa:bb:cc:dd:ee:ff");
-    let magic_bytes = get_magic_pkt(&mac);
+    let mac = args()
+        .nth(1)
+        .expect("no mac given; Usage woly aa:bb:cc:dd:ee:ff");
+
+    let mut magic_bytes = [0u8; 102];
+    get_magic_pkt(&mac, &mut magic_bytes);
 
     let socket = UdpSocket::bind("0.0.0.0:0").expect("couldnt' bind socket");
     socket.set_broadcast(true).expect("couldn't set broadcast");
-    socket.send_to(&magic_bytes, "255.255.255.255:9").expect("couldn't send data");
+    socket
+        .send_to(&magic_bytes, "255.255.255.255:9")
+        .expect("couldn't send data");
     println!("Magic packet sent to 255.255.255.255:9 for Mac {:?}", mac);
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::get_magic_pkt;
+
+    #[test]
+    fn test_magic_bytes_for_mac() {
+        let mut magic_bytes = [0u8; 102];
+        get_magic_pkt("32:1a:ff:3e:10:ef", &mut magic_bytes);
+        let expected = [
+            255, 255, 255, 255, 255, 255,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+             50,  26, 255,  62,  16, 239,
+        ];
+
+        assert_eq!(magic_bytes, expected, "Magic bytes are not created correctly");
+    }
+}