diff --git a/nixos/lib/qemu-flags.nix b/nixos/lib/qemu-flags.nix
index b310914d36c..4774fd23168 100644
--- a/nixos/lib/qemu-flags.nix
+++ b/nixos/lib/qemu-flags.nix
@@ -9,10 +9,11 @@ let
        else pkgs.lib.toHex n);
 in
 
-{
+rec {
+  qemuNicMac = net: machine: "52:54:00:12:${zeroPad net}:${zeroPad machine}";
 
   qemuNICFlags = nic: net: machine:
-    [ "-device virtio-net-pci,netdev=vlan${toString nic},mac=52:54:00:12:${zeroPad net}:${zeroPad machine}"
+    [ "-device virtio-net-pci,netdev=vlan${toString nic},mac=${qemuNicMac net machine}"
       "-netdev vde,id=vlan${toString nic},sock=$QEMU_VDE_SOCKET_${toString net}"
     ];
 
diff --git a/nixos/tests/networking.nix b/nixos/tests/networking.nix
index 3d8ab761a44..ebebbf90eb1 100644
--- a/nixos/tests/networking.nix
+++ b/nixos/tests/networking.nix
@@ -8,7 +8,9 @@ with import ../lib/testing-python.nix { inherit system pkgs; };
 with pkgs.lib;
 
 let
-  router = { config, pkgs, ... }:
+  qemu-flags = import ../lib/qemu-flags.nix { inherit pkgs; };
+
+  router = { config, pkgs, lib, ... }:
     with pkgs.lib;
     let
       vlanIfs = range 1 (length config.virtualisation.vlans);
@@ -31,16 +33,19 @@ let
         enable = true;
         interfaces = map (n: "eth${toString n}") vlanIfs;
         extraConfig = ''
-          authoritative;
         '' + flip concatMapStrings vlanIfs (n: ''
           subnet 192.168.${toString n}.0 netmask 255.255.255.0 {
             option routers 192.168.${toString n}.1;
-            # XXX: technically it's _not guaranteed_ that IP addresses will be
-            # issued from the first item in range onwards! We assume that in
-            # our tests however.
-            range 192.168.${toString n}.2 192.168.${toString n}.254;
           }
-        '');
+        '')
+        ;
+        machines = lib.flip map vlanIfs (vlan:
+          {
+            hostName = "client${toString vlan}";
+            ethernetAddress = qemu-flags.qemuNicMac vlan 1;
+            ipAddress = "192.168.${toString vlan}.2";
+          }
+        );
       };
       services.radvd = {
         enable = true;