diff --git a/umskt/src/bink2002.rs b/umskt/src/bink2002.rs
index 4e49f03..bd8c3f6 100644
--- a/umskt/src/bink2002.rs
+++ b/umskt/src/bink2002.rs
@@ -53,7 +53,8 @@ impl ProductKey {
             None => {
                 let mut rng = rand::thread_rng();
                 let random: BigInt = rng.sample(RandomBits::new(32));
-                u32::from_be_bytes(random.to_bytes_be().1[0..4].try_into().unwrap())
+                let raw = u32::from_be_bytes(random.to_bytes_be().1[0..4].try_into().unwrap());
+                raw % (bitmask(10) as u32)
             }
         };