diff --git a/src/github.com/matrix-org/dendrite/roomserver/storage/event_types_table.go b/src/github.com/matrix-org/dendrite/roomserver/storage/event_types_table.go
index 1479418a3..4a50d10d6 100644
--- a/src/github.com/matrix-org/dendrite/roomserver/storage/event_types_table.go
+++ b/src/github.com/matrix-org/dendrite/roomserver/storage/event_types_table.go
@@ -53,6 +53,9 @@ INSERT INTO event_types (event_type_nid, event_type) VALUES
 // This will result in a conflict on the event_type_unique constraint, in this
 // case we do nothing. Postgresql won't return a row in that case so we rely on
 // the caller catching the sql.ErrNoRows error and running a select to get the row.
+// We could get postgresql to return the row on a conflict by updating the row
+// but it doesn't seem like a good idea to modify the rows just to make postgres
+// return it.
 const insertEventTypeNIDSQL = "" +
 	"INSERT INTO event_types (event_type) VALUES ($1)" +
 	" ON CONFLICT ON CONSTRAINT event_type_unique" +