diff --git a/README.md b/README.md
index 5da41f5..fec86ec 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,12 @@ Prerequisite: golang installed
 
 Prerequisite: bun installed
 
+The environment variable `API_HOST` will need to be set for the middleware.
+Example `.env` in web's root:
+```
+API_HOST="http://localhost:8082/v1/"
+```
+
 1. `cd web`
 2. `bun install`