diff --git a/4.2.3-uMatrix.md b/4.2.3-uMatrix.md
index 9d7030b..c3477d4 100644
--- a/4.2.3-uMatrix.md
+++ b/4.2.3-uMatrix.md
@@ -28,6 +28,7 @@ We can easily rewrite it in the uMatrix way:
 * [::1]     * block    ### block access to IPv6 localhost
 * 192.168   * block    ### block access to LAN 192.168.x.x
 ```
+NOTE: 192.168.x.x is the most commonly used private network range. If you're using one of the [alternatives](https://en.wikipedia.org/wiki/Private_network), 10.0.0.0/8 or 172.16.0.0/12, adjust your rules accordingly. (see @crssi's [comment](https://github.com/ghacksuserjs/ghacks-user.js/issues/319#issuecomment-364119775) for details - thanks @crssi)
 
 The best practice is to use a separate browser for accessing local resources or using a temporary allow if needed ... but for those who need it permanently:
 ```