diff --git a/queries/proto/highlights.scm b/queries/proto/highlights.scm
index a859ef418..48c18906c 100644
--- a/queries/proto/highlights.scm
+++ b/queries/proto/highlights.scm
@@ -9,6 +9,7 @@
   "message"
   "enum"
   "oneof"
+  "optional"
   "repeated"
   "reserved"
   "to"