# must fail: union_O10_layers
# a layer joins no alt (codecs::described)
diff --git a/wai/wai-rs/src/http_binding/codecs.rs b/wai/wai-rs/src/http_binding/codecs.rs
index 530ae822..161ed997 100644
--- a/wai/wai-rs/src/http_binding/codecs.rs
+++ b/wai/wai-rs/src/http_binding/codecs.rs
@@ -326,7 +326,7 @@ fn described(objects: &[SeqObject]) -> Result<Vec<Element>, CodecsError> {
         let el = els[k].as_mut().expect("a base is not a layer");
         let alt = el.alts.iter_mut().find(|a| a.cap == base_cap)
             .ok_or_else(|| CodecsError::LayerUnbound(format!("wai.{cap}: its base's capability is not dispatched")))?;
-        push_unique(&mut alt.plus, cap);
+        let _ = (alt, cap);
     }
     Ok(els.into_iter().flatten().collect())
 }