diff --git a/src/proto/h1/role.rs b/src/proto/h1/role.rs
index 4bd40f69..605010ec 100644
--- a/src/proto/h1/role.rs
+++ b/src/proto/h1/role.rs
@@ -1436,7 +1436,7 @@ mod tests {
         let len = 76;
         b.bytes = len as u64;
 
-        let head = MessageHead::default();
+        let mut head = MessageHead::default();
 
         b.iter(|| {
             let mut vec = Vec::new();