diff --git a/frankbook-pro/qbittorrent/quadlet/qbittorrent.container b/frankbook-pro/qbittorrent/quadlet/qbittorrent.container
index 9f1a9e0..7f1066a 100644
--- a/frankbook-pro/qbittorrent/quadlet/qbittorrent.container
+++ b/frankbook-pro/qbittorrent/quadlet/qbittorrent.container
@@ -26,7 +26,10 @@ After=gluetun.service
 [Container]
 ContainerName=qbittorrent
 Network=gluetun.container
-Image=lscr.io/linuxserver/qbittorrent:latest
+# Pinned to the last 4.x line: Readarr's retired qB client requires the
+# qB 4.x login response (HTTP 200, body "Ok."); qB 5.x answers 204 with an
+# empty body, which fails Readarr's auth check. All other clients accept 4.x.
+Image=lscr.io/linuxserver/qbittorrent:4.6.7
 Environment=PUID=0
 Environment=PGID=0
 Environment=TZ=America/Los_Angeles