diff --git a/README.md b/README.md
index 04da7847..bb735e08 100644
--- a/README.md
+++ b/README.md
@@ -155,6 +155,7 @@ $ dotenv run -- python foo.py
 ```
 
 The CLI interface also supports reading from multiple `.env` files.
+Each file overrides the previous: if there are duplicate keys, the last file determines the final value.
 
 ```shell
 $ echo -e "a=1\nb=2\n" > .env1