diff --git a/coordinator/src/tests/tributary/mod.rs b/coordinator/src/tests/tributary/mod.rs
index 29472482..c3f98311 100644
--- a/coordinator/src/tests/tributary/mod.rs
+++ b/coordinator/src/tests/tributary/mod.rs
@@ -63,7 +63,7 @@ fn random_sign_data<R: RngCore, Id: Clone + PartialEq + Eq + Debug + Encode + De
 
     data: {
       let mut res = vec![];
-      for _ in 0 .. (rng.next_u64() % 256) {
+      for _ in 0 ..= (rng.next_u64() % 255) {
         res.push(random_vec(&mut OsRng, 512));
       }
       res