diff --git a/contestops/configure-machines.sh b/contestops/configure-machines.sh
index 6e2f61e..bdcc91f 100755
--- a/contestops/configure-machines.sh
+++ b/contestops/configure-machines.sh
@@ -14,7 +14,7 @@ parallel-ssh -x "-F local.ssh_config" -h hostlist systemctl reload nftables.serv
 
 # Uncomment these lines if machines have 4K displays. This scales display to 2x.
 # parallel-scp -x "-F local.ssh_config" -h hostlist ./set-display-scale.py /usr/local/bin/set-display-scale.py
-# parallel-ssh -x "-F local.ssh_config" -h hostlist 'DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/$(id -u contestant)/bus" runuser -u contestant -- python3 /usr/local/bin/set-display-scale.py'
+# parallel-ssh -x "-F local.ssh_config" -h hostlist runcontestant python3 /usr/local/bin/set-display-scale.py
 
 # Configure contest lock screen.
 parallel-scp -x "-F local.ssh_config" -h hostlist ./contest-lock.json /etc/contest-lock.json
diff --git a/os/layers/contestant/includes.chroot/usr/local/bin/reboot-interactive b/os/layers/contestant/includes.chroot/usr/local/bin/reboot-interactive
index 0afb060..5852805 100755
--- a/os/layers/contestant/includes.chroot/usr/local/bin/reboot-interactive
+++ b/os/layers/contestant/includes.chroot/usr/local/bin/reboot-interactive
@@ -10,7 +10,7 @@ set -eu
 
 kexec --kexec-file-syscall --load /vmlinuz --initrd=/initrd.img --append="$(cat /proc/cmdline)"
 
-if XDG_RUNTIME_DIR="/run/user/$(id -u contestant)" runuser -u contestant -- zenity --question --title="Reboot?" --text="Press Enter after inserting the boot USB stick."
+if runcontestant zenity --question --title="Reboot?" --text="Press Enter after inserting the boot USB stick."
 then
   reboot
 fi
diff --git a/os/layers/contestant/includes.chroot/usr/local/bin/runcontestant b/os/layers/contestant/includes.chroot/usr/local/bin/runcontestant
new file mode 100755
index 0000000..8bf2f86
--- /dev/null
+++ b/os/layers/contestant/includes.chroot/usr/local/bin/runcontestant
@@ -0,0 +1,7 @@
+#!/bin/bash
+# This script allows running a command as the contestant user, with environment
+# variables for that user. This allows e.g. running graphical commands.
+set -o allexport
+XDG_RUNTIME_DIR="/run/user/$(id -u contestant)"
+eval "$(runuser -u contestant -- systemctl --user show-environment)"
+exec /usr/sbin/runuser -u contestant -- "$@"