diff --git a/protocol/src/types/metadata.rs b/protocol/src/types/metadata.rs
index 59ea64d..7616266 100644
--- a/protocol/src/types/metadata.rs
+++ b/protocol/src/types/metadata.rs
@@ -205,7 +205,7 @@ pub enum Value {
 }
 
 pub trait MetaValue {
-    fn unwrap(&Value) -> &Self;
+    fn unwrap(_: &Value) -> &Self;
     fn wrap(self) -> Value;
 }