diff --git a/doc/files.md b/doc/files.md
index f1a56bcb9..902431376 100644
--- a/doc/files.md
+++ b/doc/files.md
@@ -12,5 +12,6 @@
 * fee_estimates.dat: stores statistics used to estimate minimum transaction fees and priorities required for confirmation
 * peers.dat: peer IP address database (custom format)
 * wallet.dat: personal wallet (BDB) with keys and transactions
+* zindex.dat: Optional file that stores anonset (shielded pool) stats. Only created if `zindex=1` in HUSH3.conf or `hushd -zindex` is used
 * .cookie: session RPC authentication cookie (written at start when cookie authentication is used, deleted on shutdown): since 0.12.0
 * onion_private_key: cached Tor hidden service private key for `-listenonion`: since 0.12.0