diff --git a/nixos/modules/system/boot/systemd-nspawn.nix b/nixos/modules/system/boot/systemd-nspawn.nix
index 788a13c27ca6..b462822bc2fe 100644
--- a/nixos/modules/system/boot/systemd-nspawn.nix
+++ b/nixos/modules/system/boot/systemd-nspawn.nix
@@ -19,7 +19,7 @@ let
     (assertValueOneOf "Boot" boolValues)
     (assertValueOneOf "ProcessTwo" boolValues)
     (assertValueOneOf "PrivateUsers" (boolValues ++ [ "pick" ]))
-    (assertValueOneOf "NotifyReady")
+    (assertValueOneOf "NotifyReady" boolValues)
   ];
 
   checkFiles = checkUnitConfig "Files" [