diff --git a/tests/ui-fulldeps/rustc_encodable_hygiene.rs b/tests/ui-fulldeps/rustc_encodable_hygiene.rs
index 509a6b1d22ca6..22cc3c885015a 100644
--- a/tests/ui-fulldeps/rustc_encodable_hygiene.rs
+++ b/tests/ui-fulldeps/rustc_encodable_hygiene.rs
@@ -18,6 +18,7 @@ struct A {
     a: String,
 }
 
+#[allow(dead_code)]
 trait Trait {
     fn encode(&self);
 }