diff --git a/nomos-core/src/vote/mock.rs b/nomos-core/src/vote/mock.rs
index 53b5d9f9..a6fa33d5 100644
--- a/nomos-core/src/vote/mock.rs
+++ b/nomos-core/src/vote/mock.rs
@@ -23,6 +23,8 @@ pub struct MockQc {
     count_votes: usize,
 }
 
+#[derive(Debug, thiserror::Error)]
+#[error("{0}")]
 pub struct Error(String);
 
 #[derive(Clone, Debug)]