diff --git a/README.md b/README.md
index 0e705f1..bd24cd1 100644
--- a/README.md
+++ b/README.md
@@ -270,3 +270,17 @@ without me seemingly changing anything.
 Should work after following the steps for "Audio".
 
 Can be tested in https://webrtc.github.io/test-pages
+
+## Additional
+
+### Prevent firefox sharing indicator from taking the entire tile
+
+Add the following lines to river config (before the last `exec` line):
+
+```
+riverctl float-filter-add title "Firefox — Sharing Indicator"
+riverctl float-filter-add title 'Firefox — Sharing Indicator'
+```
+
+(TODO: check which kind of quotes works)
+