diff --git a/nixos/modules/installer/tools/tools.nix b/nixos/modules/installer/tools/tools.nix
--- a/nixos/modules/installer/tools/tools.nix
+++ b/nixos/modules/installer/tools/tools.nix
@@ -86,7 +86,7 @@ in
     '';
   };
 
-  config = {
+  config = mkIf config.nix.enable {
 
     system.nixos-generate-config.configuration = mkDefault ''
       # Edit this configuration file to define what should be installed on
diff --git a/nixos/modules/services/misc/nix-daemon.nix b/nixos/modules/services/misc/nix-daemon.nix
--- a/nixos/modules/services/misc/nix-daemon.nix
+++ b/nixos/modules/services/misc/nix-daemon.nix
@@ -81,6 +81,14 @@ in
 
     nix = {
 
+      enable = mkOption {
+        type = types.bool;
+        default = true;
+        description = ''
+          If disabled, Nix will not be available on the built NixOS system.
+        '';
+      };
+
       package = mkOption {
         type = types.package;
         default = pkgs.nix;
@@ -498,7 +506,7 @@ in
 
   ###### implementation
 
-  config = {
+  config = mkIf cfg.enable {
 
     nix.binaryCachePublicKeys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
     nix.binaryCaches = [ "https://cache.nixos.org/" ];
diff --git a/nixos/modules/services/misc/nix-gc.nix b/nixos/modules/services/misc/nix-gc.nix
--- a/nixos/modules/services/misc/nix-gc.nix
+++ b/nixos/modules/services/misc/nix-gc.nix
@@ -48,7 +48,7 @@ in
 
   ###### implementation
 
-  config = {
+  config = mkIf config.nix.enable {
 
     systemd.services.nix-gc =
       { description = "Nix Garbage Collector";
diff --git a/nixos/modules/services/misc/nix-optimise.nix b/nixos/modules/services/misc/nix-optimise.nix
--- a/nixos/modules/services/misc/nix-optimise.nix
+++ b/nixos/modules/services/misc/nix-optimise.nix
@@ -36,7 +36,7 @@ in
 
   ###### implementation
 
-  config = {
+  config = mkIf config.nix.enable {
 
     systemd.services.nix-optimise =
       { description = "Nix Store Optimiser";
diff --git a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py
--- a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py
+++ b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py
@@ -124,18 +124,19 @@ def mkdir_p(path):
             raise
 
 def get_generations(profile=None):
-    gen_list = subprocess.check_output([
-        "@nix@/bin/nix-env",
-        "--list-generations",
-        "-p",
-        "/nix/var/nix/profiles/%s" % ("system-profiles/" + profile if profile else "system"),
-        "--option", "build-users-group", ""],
-        universal_newlines=True)
-    gen_lines = gen_list.split('\n')
-    gen_lines.pop()
+    generation_dir = "/nix/var/nix/profiles/%s" % ("system-profiles" if profile else "",)
+    profile_name = profile if profile else "system"
+    generations = []
+    for gen_entry in os.scandir(generation_dir):
+        gen_name = gen_entry.name
+        if not (gen_name.startswith(profile_name + '-') and gen_name.endswith('-link')):
+            continue
+        gen_num = gen_name[len(profile_name+'-'):-len('-link')]
+        generations.append(int(gen_num))
+    generations.sort()
 
     configurationLimit = @configurationLimit@
-    return [ (profile, int(line.split()[0])) for line in gen_lines ][-configurationLimit:]
+    return [ (profile, gen_num) for gen_num in sorted(generations) ][-configurationLimit:]
 
 def remove_old_entries(gens):
     rex_profile = re.compile("^@efiSysMountPoint@/loader/entries/nixos-(.*)-generation-.*\.conf$")
diff --git a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
--- a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
+++ b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
@@ -16,8 +16,6 @@ let
 
     systemd = config.systemd.package;
 
-    nix = config.nix.package.out;
-
     timeout = if config.boot.loader.timeout != null then config.boot.loader.timeout else "";
 
     editor = if cfg.editor then "True" else "False";