diff --git a/borgbackup.nix b/borgbackup.nix
index 44306a6..7fde887 100644
--- a/borgbackup.nix
+++ b/borgbackup.nix
@@ -24,6 +24,7 @@
       "**/*Trash"
       # already cloud apps
       "**/.mozilla/firefox"
+      "**/.thunderbird"
       # build-output directories
       "**/target"
       "**/result"