diff --git a/deploy/scripts/setup-pi-kiosk.sh b/deploy/scripts/setup-pi-kiosk.sh
index 9bbae80..4df3a1b 100644
--- a/deploy/scripts/setup-pi-kiosk.sh
+++ b/deploy/scripts/setup-pi-kiosk.sh
@@ -164,7 +164,9 @@ if [ "${INSTALL_KIOSK}" = "1" ]; then
   if ! id -u bfkiosk >/dev/null 2>&1; then
     useradd -m -s /usr/sbin/nologin bfkiosk
   fi
-  for grp in video render input audio seat; do
+  # Debian's seatd uses -g video (no separate 'seat' group) — only join groups
+  # that actually exist on this system.
+  for grp in video render input audio; do
     if getent group "$grp" >/dev/null; then
       usermod -a -G "$grp" bfkiosk
     fi
diff --git a/deploy/systemd/betterframe-kiosk.service b/deploy/systemd/betterframe-kiosk.service
index 62813ec..65e9d3e 100644
--- a/deploy/systemd/betterframe-kiosk.service
+++ b/deploy/systemd/betterframe-kiosk.service
@@ -10,7 +10,7 @@ After=getty@tty1.service
 Type=simple
 User=bfkiosk
 Group=bfkiosk
-SupplementaryGroups=video render input audio seat
+SupplementaryGroups=video render input audio
 PAMName=cage
 TTYPath=/dev/tty1
 TTYReset=yes