diff --git a/src/pg/sql/42_observatory_exploration.sql b/src/pg/sql/42_observatory_exploration.sql
index e0ab8ef..9dfc866 100644
--- a/src/pg/sql/42_observatory_exploration.sql
+++ b/src/pg/sql/42_observatory_exploration.sql
@@ -115,5 +115,6 @@ BEGIN
         $1 && bounds::box2d
   $string$ || timespan_query
   USING geom;
+  RETURN;
 END
 $$ LANGUAGE plpgsql;