diff --git a/flake.lock b/flake.lock
index 05f0e4b..108c259 100644
--- a/flake.lock
+++ b/flake.lock
@@ -55,6 +55,22 @@
         "type": "github"
       }
     },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1644472683,
+        "narHash": "sha256-sP6iM4NksOYO6NFfTJ96cg+ClPnq6cdY30xKA1iYtyU=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "7adc9c14ec74b27358a8df9b973087e351425a79",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-21.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "artiq": "artiq"
@@ -62,10 +78,7 @@
     },
     "sipyco": {
       "inputs": {
-        "nixpkgs": [
-          "artiq",
-          "nixpkgs"
-        ]
+        "nixpkgs": "nixpkgs_2"
       },
       "locked": {
         "lastModified": 1644634510,