diff --git a/nixos/modules/system/boot/systemd.nix b/nixos/modules/system/boot/systemd.nix
index 7d528348918..4705ceb8086 100644
--- a/nixos/modules/system/boot/systemd.nix
+++ b/nixos/modules/system/boot/systemd.nix
@@ -630,6 +630,12 @@ in
 
   config = {
 
+    assertions = mapAttrsToList (name: service: {
+      assertion = !hasAttr "Type" service.serviceConfig || service.serviceConfig.Type != "oneshot"
+        || !hasAttr "Restart" service.serviceConfig || service.serviceConfig.Restart == "no";
+      message = "${name}: Type=oneshot services must have Restart=no";
+    }) cfg.services;
+
     system.build.units = units;
 
     environment.systemPackages = [ systemd ];