diff --git a/README.md b/README.md
index deaa039..522b766 100644
--- a/README.md
+++ b/README.md
@@ -212,6 +212,7 @@ Usage of oauth2_proxy:
   -http-address string: [http://]<addr>:<port> or unix://<path> to listen on for HTTP clients (default "127.0.0.1:4180")
   -https-address string: <addr>:<port> to listen on for HTTPS clients (default ":443")
   -login-url string: Authentication endpoint
+  -oidc-issuer-url: the OpenID Connect issuer URL. ie: "https://accounts.google.com"
   -pass-access-token: pass OAuth access_token to upstream via X-Forwarded-Access-Token header
   -pass-authorization-header: pass OIDC IDToken to upstream via Authorization Bearer header
   -pass-basic-auth: pass HTTP Basic Auth, X-Forwarded-User and X-Forwarded-Email information to upstream (default true)