diff --git a/scripts-available/CDB_JenksBins.sql b/scripts-available/CDB_JenksBins.sql
index 4b8328b..9db1ad6 100644
--- a/scripts-available/CDB_JenksBins.sql
+++ b/scripts-available/CDB_JenksBins.sql
@@ -117,7 +117,7 @@ BEGIN
 
     RETURN (best_result)[2:array_upper(best_result, 1)];
 END;
-$$ language plpgsql IMMUTABLE PARALLEL RESTRICTED;
+$$ language plpgsql VOLATILE PARALLEL RESTRICTED;