diff --git a/tests/ui/missing-doc-impl.rs b/tests/ui/missing-doc-impl.rs
index 1317521f7366..57af84dcdf4d 100644
--- a/tests/ui/missing-doc-impl.rs
+++ b/tests/ui/missing-doc-impl.rs
@@ -46,7 +46,7 @@ pub trait D {
 }
 
 /// dox
-pub trait E {
+pub trait E: Sized {
     type AssociatedType;
     type AssociatedTypeDef = Self;