diff --git a/bgpwtf/machines/modules/gretap.nix b/bgpwtf/machines/modules/gretap.nix
index f4e1a7b..7d3d847 100644
--- a/bgpwtf/machines/modules/gretap.nix
+++ b/bgpwtf/machines/modules/gretap.nix
@@ -56,7 +56,7 @@
     ];
     serviceConfig = {
       Type = "oneshot";
-      ExecStart = "${pkgs.iproute}/bin/ip link add name ${name} type gretap remote ${value.remoteV4} local ${value.localV4} key ${toString value.id}";
+      ExecStart = "${pkgs.iproute2}/bin/ip link add name ${name} type gretap remote ${value.remoteV4} local ${value.localV4} key ${toString value.id}";
     };
   }) cfg.interfaces;
 }
diff --git a/cluster/nix/default.nix b/cluster/nix/default.nix
index a5f5082..39d693b 100644
--- a/cluster/nix/default.nix
+++ b/cluster/nix/default.nix
@@ -1,10 +1,11 @@
 let
-  pkgs = import (fetchGit {
-    name = "nixos-unstable-2020-08-22";
-    url = https://github.com/nixos/nixpkgs-channels/;
-    rev = "c59ea8b8a0e7f927e7291c14ea6cd1bd3a16ff38";
-  });
-
+  # Tracking nixos-unstable as of 2021-01-31.
+  nixpkgsCommit = "44ad80ab1036c5cc83ada4bfa451dac9939f2a10";
+  nixpkgsSrc = fetchTarball {
+    url = "https://github.com/NixOS/nixpkgs/archive/${nixpkgsCommit}.tar.gz";
+    sha256 = "1b61nzvy0d46cspy07szkc0rggacxiqg9v1py27pkqpj7rvawfsk";
+  };
+  pkgs = import nixpkgsSrc;
   cfg = {
     overlays = [
       (import ./provision.nix)
diff --git a/default.nix b/default.nix
index cc761d4..4540157 100644
--- a/default.nix
+++ b/default.nix
@@ -7,11 +7,11 @@
 
   readTree = import ./nix/readtree.nix {};
 
-  # Tracking nixos-unstable as of 2020-08-22.
-  nixpkgsCommit = "c59ea8b8a0e7f927e7291c14ea6cd1bd3a16ff38";
+  # Tracking nixos-unstable as of 2021-01-31.
+  nixpkgsCommit = "44ad80ab1036c5cc83ada4bfa451dac9939f2a10";
   nixpkgsSrc = fetchTarball {
-    url = "https://github.com/NixOS/nixpkgs-channels/archive/${nixpkgsCommit}.tar.gz";
-    sha256 = "1ak7jqx94fjhc68xh1lh35kh3w3ndbadprrb762qgvcfb8351x8v";
+    url = "https://github.com/NixOS/nixpkgs/archive/${nixpkgsCommit}.tar.gz";
+    sha256 = "1b61nzvy0d46cspy07szkc0rggacxiqg9v1py27pkqpj7rvawfsk";
   };
   nixpkgs = import nixpkgsSrc {
     config.allowUnfree = true;