diff --git a/README.md b/README.md
index 28a54d5..0cbd747 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,11 @@
 # code.dumpstack.io
 
+[Download NixOS installation ISO](https://nixos.org/nixos/download.html)
+
+Notes:
+1. I assume that latest **stable** (e.g. 19.03) ISO will be used for installation.
+2. You need to change hostname in `configuration.nix:9`.
+
 ## Installation
 
     parted /dev/vda mklabel msdos
@@ -8,9 +14,13 @@
     mount /dev/vda1 /mnt/
 
     nix-env -iA nixos.gitMinimal
-	git clone https://code.dumpstack.io/infra/code.dumpstack.io.git /mnt/etc/nixos/
+    git clone https://code.dumpstack.io/infra/code.dumpstack.io.git /mnt/etc/nixos/
 
     nixos-generate-config --root /mnt
 
     nixos-install
     reboot
+
+## After install
+
+    nix-channel --add https://nixos.org/channels/nixos-unstable unstable
diff --git a/configuration.nix b/configuration.nix
index 109a3bc..22d157c 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -1,9 +1,19 @@
+# nix-channel --add https://nixos.org/channels/nixos-19.03 nixos
+# nix-channel --add https://nixos.org/channels/nixos-unstable unstable
+# nix-channel --update
+#
 { config, pkgs, ... }:
 let
+  unstable = import <unstable> {};
   secrets = import ./secrets.nix;
   hostname = "code.dumpstack.io";
 in {
-  imports = [ ./hardware-configuration.nix ];
+  disabledModules = [ "services/misc/gitea.nix" ];
+
+  imports = [
+    ./hardware-configuration.nix
+    <unstable/nixos/modules/services/misc/gitea.nix>
+  ];
 
   boot.loader.grub.enable = true;
   boot.loader.grub.version = 2;
@@ -62,7 +72,7 @@ in {
     fi
   '';
 
-  system.stateVersion = "18.09";
+  system.stateVersion = "19.03";
   system.autoUpgrade.enable = true;
 
   nix = {