diff --git a/nixos/modules/virtualisation/qemu-guest-agent.nix b/nixos/modules/virtualisation/qemu-guest-agent.nix
index 9f12177922be..aa66f7b682ad 100644
--- a/nixos/modules/virtualisation/qemu-guest-agent.nix
+++ b/nixos/modules/virtualisation/qemu-guest-agent.nix
@@ -25,7 +25,7 @@ in
     {
 
       services.udev.extraRules = ''
-        SUBSYSTEM=="virtio-ports", ATTR{name}=="org.qemu.guest_agent.0", TAG+="systemd" ENV{SYSTEMD_WANTS}="qemu-guest-agent.service"
+        SUBSYSTEM=="virtio-ports", ATTR{name}=="org.qemu.guest_agent.0", TAG+="systemd", ENV{SYSTEMD_WANTS}="qemu-guest-agent.service"
       '';
 
       systemd.services.qemu-guest-agent = {