diff --git a/README.md b/README.md
index 529fb1d..c0cc3f0 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,7 @@ To enable social login, you should have OAuth client token in a `.env` file:
 You can copy from `example.env`
 
     # .env
+    BASE_URL=https://example.com
     GOOGLE_CLIENT_ID=...
     GOOGLE_CLIENT_SECRET=...
 
diff --git a/docker-compose.prod.yml b/docker-compose.prod.yml
index a78bc6e..006532b 100644
--- a/docker-compose.prod.yml
+++ b/docker-compose.prod.yml
@@ -36,7 +36,7 @@ services:
       - mongo:/data/db
       - ./mongo-init.js:/docker-entrypoint-initdb.d/mongo-init.js:ro
     environment:
-      - BASE_URL=https://example.com
+      - BASE_URL=${BASE_URL}
       - MONGO_INITDB_ROOT_USERNAME=admin
       - MONGO_INITDB_ROOT_PASSWORD=admin-password
       - MONGO_USER=user