diff --git a/thrift/annotation/rust.thrift b/thrift/annotation/rust.thrift
index 5d4e7eacbaee4..e22294010d7e1 100644
--- a/thrift/annotation/rust.thrift
+++ b/thrift/annotation/rust.thrift
@@ -80,6 +80,7 @@ struct Exhaustive {
 
 @scope.Struct
 @scope.Typedef
+@scope.Union
 struct Ord {
 // # `rust.Ord`
 //