diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 96915ea..31b0fdd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,7 +15,7 @@ jobs:
       - uses: cachix/install-nix-action@v23
         with:
           github_access_token: ${{ secrets.GH_TOKEN }}
-      - uses: cachix/cachix-action@v12
+      - uses: cachix/cachix-action@v13
         with:
           name: efishery
           # If you chose signing key for write access
diff --git a/go/flake.lock b/go/flake.lock
index 68cbe47..243db1a 100644
--- a/go/flake.lock
+++ b/go/flake.lock
@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1675698036,
-        "narHash": "sha256-BgsQkQewdlQi8gapJN4phpxkI/FCE/2sORBaFcYbp/A=",
+        "lastModified": 1699343069,
+        "narHash": "sha256-s7BBhyLA6MI6FuJgs4F/SgpntHBzz40/qV0xLPW6A1Q=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "1046c7b92e908a1202c0f1ba3fc21d19e1cf1b62",
+        "rev": "ec750fd01963ab6b20ee1f0cb488754e8036d89d",
         "type": "github"
       },
       "original": {
@@ -22,13 +22,31 @@
         "utils": "utils"
       }
     },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    },
     "utils": {
+      "inputs": {
+        "systems": "systems"
+      },
       "locked": {
-        "lastModified": 1667395993,
-        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "lastModified": 1694529238,
+        "narHash": "sha256-zsNZZGTGnMOf9YpHKJqMSsa0dXbfmxeoJ7xHlrt+xmY=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
+        "rev": "ff7b65b44d01cf9ba6a71320833626af21126384",
         "type": "github"
       },
       "original": {
diff --git a/go/flake.nix b/go/flake.nix
index e18373f..ec6a7d0 100644
--- a/go/flake.nix
+++ b/go/flake.nix
@@ -10,7 +10,7 @@
 
     utils.lib.eachDefaultSystem (system:
       let
-        goVersion = 19;
+        goVersion = 21;
         overlays = [ (final: prev: { go = prev."go_1_${toString goVersion}"; }) ];
         pkgs = import nixpkgs { inherit overlays system; };