diff --git a/environment.nix b/environment.nix
index 16be199..2eeb32d 100644
--- a/environment.nix
+++ b/environment.nix
@@ -1,6 +1,12 @@
 { config, pkgs, ... }:
 
 {
+  # Nombre de process d'installation en parrallèle effectués par Nix
+  nix.buildCores = 0;
+
+  # The NixOS release to be compatible with for stateful data such as databases.
+  system.stateVersion = "16.03";
+
   # List packages installed in system profile. To search by name, run:
   # $ nix-env -qaP | grep wget
   environment = {