diff --git a/flake.lock b/flake.lock
index 770e2a5f..0f455597 100644
--- a/flake.lock
+++ b/flake.lock
@@ -18,16 +18,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1628776130,
-        "narHash": "sha256-EyzdilgzoO8YCgck1lkOF1Bp+QVEazJBtuG5GkVY6xg=",
-        "owner": "NixOS",
+        "lastModified": 1630612789,
+        "narHash": "sha256-f1q5ExkMX2CBqBcRmrlnpewADt3EjhyncP/PfwUhK/Q=",
+        "owner": "L-as",
         "repo": "nixpkgs",
-        "rev": "ad6e733d633802620b5eec9be91e837973eac18a",
+        "rev": "11f9ff27bc66bf653ccbbfae1412e6f5705e4a5c",
         "type": "github"
       },
       "original": {
-        "owner": "NixOS",
-        "ref": "nixos-21.05",
+        "owner": "L-as",
+        "ref": "alliance",
         "repo": "nixpkgs",
         "type": "github"
       }
diff --git a/flake.nix b/flake.nix
index 2a8074c9..949fdda0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,7 +4,7 @@
   description = "Coriolis is a free database, placement tool and routing tool for VLSI design.";
 
   # Nixpkgs / NixOS version to use.
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs?ref=nixos-21.05";
+  inputs.nixpkgs.url = "github:L-as/nixpkgs?ref=alliance"; # for alliance
   inputs.alliance-check-toolkit.url = "git+https://gitlab.lip6.fr/vlsi-eda/alliance-check-toolkit.git";
   inputs.alliance-check-toolkit.flake = false;