diff --git a/encoding/openapi/testdata/oneof.cue b/encoding/openapi/testdata/oneof.cue
index a78285d..95935ac 100644
--- a/encoding/openapi/testdata/oneof.cue
+++ b/encoding/openapi/testdata/oneof.cue
@@ -1,3 +1,7 @@
+// OpenAPI title.
+
+$version: "v1alpha1"
+
 T :: {
 	shared: int
 }
@@ -17,7 +21,7 @@
 
 MyInt :: int
 
-Foo: {
+Foo :: {
 	include: T
 	exclude: [...T]
 	count: MyInt