diff --git a/B2C.md b/B2C.md
index 19a5256..259074e 100644
--- a/B2C.md
+++ b/B2C.md
@@ -7,4 +7,5 @@
 ```
 OAUTH2_ENABLED=true
 OAUTH2_B2C_ENABLED=true
+OAUTH2_USERNAME_MAP=sub
 ```