diff --git a/modules/system/activation/top-level.nix b/modules/system/activation/top-level.nix
index 265f06a5a9d3..aa79fb3698dc 100644
--- a/modules/system/activation/top-level.nix
+++ b/modules/system/activation/top-level.nix
@@ -38,6 +38,9 @@ let
       description = ''
         Name of the kernel file to be passed to the bootloader.
       '';
+      merge = kernelFiles:
+        builtins.head (map (f: assert f == builtins.head kernelFiles; f)
+          kernelFiles);
     };
 
     system.copySystemConfiguration = pkgs.lib.mkOption {