diff --git a/src/core/service.c b/src/core/service.c
index 792ec99a00..af5a2decf1 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -668,7 +668,8 @@ static int service_setup_bus_name(Service *s) {
 
         assert(s);
 
-        if (s->type != SERVICE_DBUS)
+        /* If s->bus_name is not set, then the unit will be refused by service_verify() later. */
+        if (s->type != SERVICE_DBUS || !s->bus_name)
                 return 0;
 
         r = unit_add_dependency_by_name(UNIT(s), UNIT_REQUIRES, SPECIAL_DBUS_SOCKET, true, UNIT_DEPENDENCY_FILE);
diff --git a/test/units/testsuite-42.sh b/test/units/testsuite-42.sh
index e47fab46e6..4e6be7e06e 100755
--- a/test/units/testsuite-42.sh
+++ b/test/units/testsuite-42.sh
@@ -65,6 +65,10 @@ test -f /run/dbus1
 systemd-run --unit=dbus2.service --wait -p StandardOutput=tty -p StandardError=tty -p Type=dbus -p BusName=systemd.test.ExecStopPost -p ExecStopPost='/bin/touch /run/dbus2' true
 test -f /run/dbus2
 
+# https://github.com/systemd/systemd/issues/19920
+systemd-run --unit=dbus3.service --wait -p StandardOutput=tty -p StandardError=tty -p Type=dbus -p ExecStopPost='/bin/touch /run/dbus3' true \
+     && { echo 'unexpected success'; exit 1; }
+
 cat >/tmp/notify1.sh <<EOF
 #!/usr/bin/env bash