diff --git a/ipcert.md b/ipcert.md
index 32ad78c..26028a5 100644
--- a/ipcert.md
+++ b/ipcert.md
@@ -1,7 +1,7 @@
 Just use the ip address as the `-d` parameter:
 
 ```
-acme.sh  --issue  -d 1.1.1.1  --w /etc/apache/xxxxxx
+acme.sh  --issue  -d 1.1.1.1  -w /etc/apache/xxxxxx
 ```
 
 As the rfc 8738 requires: https://tools.ietf.org/html/rfc8738