diff --git a/overlay.d/05core/usr/lib/systemd/system-preset/40-coreos.preset b/overlay.d/05core/usr/lib/systemd/system-preset/40-coreos.preset
index 89a4bc8d21..d121675c61 100644
--- a/overlay.d/05core/usr/lib/systemd/system-preset/40-coreos.preset
+++ b/overlay.d/05core/usr/lib/systemd/system-preset/40-coreos.preset
@@ -13,3 +13,5 @@ enable afterburn-firstboot-checkin.service
 enable afterburn-sshkeys@.service
 # Update agent
 enable zincati.service
+# Testing aid
+enable coreos-liveiso-success.service
diff --git a/overlay.d/05core/usr/lib/systemd/system/coreos-liveiso-success.service b/overlay.d/05core/usr/lib/systemd/system/coreos-liveiso-success.service
new file mode 100644
index 0000000000..c3f4a94d54
--- /dev/null
+++ b/overlay.d/05core/usr/lib/systemd/system/coreos-liveiso-success.service
@@ -0,0 +1,23 @@
+# This is used by our test framework in coreos-assembler
+# since we don't have a way to inject testing configuration
+# via Ignition to test this scenario.
+[Unit]
+Description=CoreOS Live ISO virtio success
+Documentation=https://github.com/coreos/fedora-coreos-config
+# Only run on the Live ISO, and only if there's no Ignition config;
+# the second bits here invert the conditionals in coreos-liveiso-network-kargs.service.
+ConditionKernelCommandLine=coreos.liveiso
+ConditionPathExists=!/config.ign
+ConditionVirtualization=|kvm
+ConditionVirtualization=|qemu
+# Start running late to help ensure that the below conditional works
+After=systemd-user-sessions.service
+ConditionPathExists=/dev/virtio-ports/coreos.liveiso-success
+
+[Service]
+Type=simple
+# See https://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-messages.h
+ExecStart=/bin/sh -c 'journalctl -b -f -o cat -u systemd-logind.service MESSAGE_ID=8d45620c1a4348dbb17410da57c60c66 | head -1 >dev/null; echo coreos-liveiso-success > /dev/virtio-ports/coreos.liveiso-success'
+
+[Install]
+WantedBy=multi-user.target