diff --git a/README.md b/README.md
index 9130d31..f2cee6c 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,8 @@ Excel password terminator
 
 This script removes passwords in an Excel file.
 
+**Warning:**  this script does not work if the file is encrypted!
+
 Requirements
 ------------