diff --git a/nixos/modules/system/boot/binfmt.nix b/nixos/modules/system/boot/binfmt.nix
index 2408ecc80d22..fdb4d0e4c7fb 100644
--- a/nixos/modules/system/boot/binfmt.nix
+++ b/nixos/modules/system/boot/binfmt.nix
@@ -248,6 +248,7 @@ in {
         description = ''
           List of systems to emulate. Will also configure Nix to
           support your new systems.
+          Warning: the builder can execute all emulated systems within the same build, which introduces impurities in the case of cross compilation.
         '';
         type = types.listOf types.str;
       };