diff --git a/src/bink1998.rs b/src/bink1998.rs
index 2527c97..d4dc575 100644
--- a/src/bink1998.rs
+++ b/src/bink1998.rs
@@ -26,7 +26,8 @@ const EVERYTHING_ELSE: u8 = HASH_LENGTH_BITS + SERIAL_LENGTH_BITS + UPGRADE_LENG
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub struct ProductKey {
     upgrade: bool,
-    serial: u32,
+    channel_id: u32,
+    sequence: u32,
     hash: u32,
     signature: u64,
 }
@@ -59,7 +60,8 @@ impl ProductKey {
             &curve.gen_point,
             &private_key.gen_order,
             &private_key.private_key,
-            channel_id * 1_000_000 + sequence,
+            channel_id,
+            sequence,
             upgrade,
         )?;
 
@@ -85,7 +87,8 @@ impl ProductKey {
         base_point: &EcPoint,
         gen_order: &BigNum,
         private_key: &BigNum,
-        serial: u32,
+        channel_id: u32,
+        sequence: u32,
         upgrade: bool,
     ) -> Result<Self> {
         let mut num_context = BigNumContext::new().unwrap();
@@ -97,6 +100,7 @@ impl ProductKey {
 
         let mut ek: BigNum;
 
+        let serial = channel_id * 1_000_000 + sequence;
         let data = serial << 1 | upgrade as u32;
 
         let product_key = loop {
@@ -139,7 +143,8 @@ impl ProductKey {
             if signature <= bitmask(55) {
                 break Self {
                     upgrade,
-                    serial,
+                    channel_id,
+                    sequence,
                     hash,
                     signature,
                 };
@@ -182,7 +187,8 @@ impl ProductKey {
         let mut y_bin = y.to_vec_padded(FIELD_BYTES as i32)?;
         y_bin.reverse();
 
-        let data = self.serial << 1 | self.upgrade as u32;
+        let serial = self.channel_id * 1_000_000 + self.sequence;
+        let data = serial << 1 | self.upgrade as u32;
 
         msg_buffer[0..4].copy_from_slice(&data.to_le_bytes());
         msg_buffer[4..4 + FIELD_BYTES].copy_from_slice(&x_bin);
@@ -206,9 +212,13 @@ impl ProductKey {
         let serial = reader.read_u32(SERIAL_LENGTH_BITS)?;
         let upgrade = reader.read_bool()?;
 
+        let sequence = serial % 1_000_000;
+        let channel_id = serial / 1_000_000;
+
         Ok(Self {
             upgrade,
-            serial,
+            channel_id,
+            sequence,
             hash,
             signature,
         })
@@ -217,9 +227,11 @@ impl ProductKey {
     fn pack(&self) -> Vec<u8> {
         let mut packed_key: u128 = 0;
 
+        let serial = self.channel_id * 1_000_000 + self.sequence;
+
         packed_key |= (self.signature as u128) << EVERYTHING_ELSE;
         packed_key |= (self.hash as u128) << (SERIAL_LENGTH_BITS + UPGRADE_LENGTH_BITS);
-        packed_key |= (self.serial as u128) << UPGRADE_LENGTH_BITS;
+        packed_key |= (serial as u128) << UPGRADE_LENGTH_BITS;
         packed_key |= self.upgrade as u128;
 
         packed_key
@@ -287,7 +299,8 @@ mod tests {
     fn pack_test() {
         let key = super::ProductKey {
             upgrade: false,
-            serial: 640010550,
+            channel_id: 640,
+            sequence: 10550,
             hash: 39185432,
             signature: 6939952665262054,
         };