diff --git a/.env.example b/.env.example
index 3d56c58538..540fe6af62 100644
--- a/.env.example
+++ b/.env.example
@@ -34,3 +34,6 @@ FMTM_DB_HOST=fmtm-db
 FMTM_DB_USER=fmtm
 FMTM_DB_PASSWORD=fmtm
 FMTM_DB_NAME=fmtm
+
+### Underpass (optional) ###
+# UNDERPASS_API_URL=