diff --git a/README.md b/README.md
index ed0c42e..67cf3be 100644
--- a/README.md
+++ b/README.md
@@ -169,6 +169,10 @@ webui:
   environment:
     AUTH_USER_PASS: "username:$2y$10$DSTi9o..."
 ```
+Docker Compose treats $ as the start of an environment variable.
+Since bcrypt hashes can contain $ characters, Compose will try to substitute them and may emit warnings or truncate the value.
+To pass a literal ''$'', you must escape it as ''$$''
+
 
 ### Running