diff --git a/docs/manifest.appcache b/docs/manifest.appcache
index 03144a0b9e..9b96154259 100644
--- a/docs/manifest.appcache
+++ b/docs/manifest.appcache
@@ -47,6 +47,7 @@ https://fonts.gstatic.com/s/opensans/v10/k3k702ZOKiLJc3WVjuplzBampu5_7CjHW5spxoe
 /static/img/friends/github.svg
 /static/img/friends/leveldb.svg
 /static/img/friends/bluesky.svg
+/static/img/friends/mastodon.svg
 
 /static/img/browser-logos/android_32x32.png
 /static/img/browser-logos/chrome-android_32x32.png