diff --git a/SysadminTips.page b/SysadminTips.page
index b2d6108..f360b29 100644
--- a/SysadminTips.page
+++ b/SysadminTips.page
@@ -91,6 +91,7 @@ After Debian/Ubuntu upgrade, merge local config files according to config files
 
 ```
 for file in $(find /etc -iname '*.dpkg-dist'); do vimdiff ${file%%.dpkg-dist} $file; done
+for file in $(find /etc -iname '*.dpkg-old'); do vimdiff ${file%%.dpkg-old} $file; done
 for file in $(find /etc -iname '*.ucf-dist'); do vimdiff ${file%%.ucf-dist} $file; done
 ```