diff --git a/Quick-guide:-popup-user-interface.md b/Quick-guide:-popup-user-interface.md
index f35b5d1..32fc4c8 100644
--- a/Quick-guide:-popup-user-interface.md
+++ b/Quick-guide:-popup-user-interface.md
@@ -151,4 +151,6 @@ Because of security and privacy concerns, many prefer to block all web fonts by
 
     no-remote-fonts: * true
 
-This will block all web fonts everywhere by default, and in this case you can toggle off the switch to allow web fonts on a per-site basis.
\ No newline at end of file
+This will block all web fonts everywhere by default, and in this case you can toggle off the switch to allow web fonts on a per-site basis.
+
+**Caveat:** Chromium's webRequest API [does not specifically report requests of type `font`](https://developer.chrome.com/extensions/webRequest#type-ResourceType), fonts are reported as type `other`. Whether a request is for a font resource is inferred by uBlock using the "extension" of the path part of a URL. However a URL can be anything really, regardless of request type, so for Chromium-based browsers, uBlock **may** have to block a font **after** the request is made, when the response headers are received from the remote server -- as the response headers allow to identify for sure the type of a resource.