diff --git a/nixos/modules/virtualisation/nixos-containers.nix b/nixos/modules/virtualisation/nixos-containers.nix
index d54e2ed3f3ae..c3949564d4bd 100644
--- a/nixos/modules/virtualisation/nixos-containers.nix
+++ b/nixos/modules/virtualisation/nixos-containers.nix
@@ -515,6 +515,10 @@ in
                     in [ extraConfig ] ++ (map (x: x.value) defs);
                   prefix = [ "containers" name ];
                   inherit (config) specialArgs;
+
+                  # The system is inherited from the host above.
+                  # Set it to null, to remove the "legacy" entrypoint's non-hermetic default.
+                  system = null;
                 }).config;
               };
             };
diff --git a/nixos/tests/containers-imperative.nix b/nixos/tests/containers-imperative.nix
index 3007efaf8871..22b664a90e17 100644
--- a/nixos/tests/containers-imperative.nix
+++ b/nixos/tests/containers-imperative.nix
@@ -25,6 +25,10 @@ import ./make-test-python.nix ({ pkgs, lib, ... }: {
               system.stateVersion = "18.03";
             };
           };
+
+          # The system is inherited from the host above.
+          # Set it to null, to remove the "legacy" entrypoint's non-hermetic default.
+          system = null;
         };
       in with pkgs; [
         stdenv stdenvNoCC emptyContainer.config.containers.foo.path
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 22efeb42ebff..fa0947bf2db4 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -39009,6 +39009,10 @@ with pkgs;
                   then configuration
                   else [configuration]
                 );
+
+                # The system is inherited from the current pkgs above.
+                # Set it to null, to remove the "legacy" entrypoint's non-hermetic default.
+                system = null;
             };
       in
         c.config.system.build // c;