diff --git a/flake.lock b/flake.lock
index aeea3f8..4b0a963 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,19 +2,16 @@
   "nodes": {
     "devshell": {
       "inputs": {
-        "flake-utils": [
-          "flake-utils"
-        ],
         "nixpkgs": [
           "nixpkgs"
         ]
       },
       "locked": {
-        "lastModified": 1713532798,
-        "narHash": "sha256-wtBhsdMJA3Wa32Wtm1eeo84GejtI43pMrFrmwLXrsEc=",
+        "lastModified": 1764011051,
+        "narHash": "sha256-M7SZyPZiqZUR/EiiBJnmyUbOi5oE/03tCeFrTiUZchI=",
         "owner": "numtide",
         "repo": "devshell",
-        "rev": "12e914740a25ea1891ec619bb53cf5e6ca922e40",
+        "rev": "17ed8d9744ebe70424659b0ef74ad6d41fc87071",
         "type": "github"
       },
       "original": {
@@ -28,11 +25,11 @@
         "systems": "systems"
       },
       "locked": {
-        "lastModified": 1710146030,
-        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
         "type": "github"
       },
       "original": {
@@ -64,27 +61,27 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1764948399,
-        "narHash": "sha256-yFQk8eqAX41XTZ20q4AV8QKvO3AcYgkuTE0IX1S8znA=",
+        "lastModified": 1764831616,
+        "narHash": "sha256-OtzF5wBvO0jgW1WW1rQU9cMGx7zuvkF7CAVJ1ypzkxA=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "97b06a59ddaf7f110b3846ce789a52e0486b42db",
+        "rev": "c97c47f2bac4fa59e2cbdeba289686ae615f8ed4",
         "type": "github"
       },
       "original": {
         "owner": "nixos",
-        "ref": "release-25.11",
+        "ref": "nixos-25.11",
         "repo": "nixpkgs",
         "type": "github"
       }
     },
     "nixpkgs-unstable": {
       "locked": {
-        "lastModified": 1713995654,
-        "narHash": "sha256-S+4C0H9w7H9tSv1RviD/otsTmf1ECuxJMJ/j1t9gjPE=",
+        "lastModified": 1764951420,
+        "narHash": "sha256-oLJXP0fb5hyUvHGKAWdtjhl1/4ivxXy3HsuMMTTxrd8=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "ce6da85c2dc9e659bef799c2ed053771e1bb8ee3",
+        "rev": "0b784f7c32b9bbab8a599ccc6b4acc58f42d6f4f",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 4e8989c..89ba34c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -3,7 +3,9 @@
   inputs = {
     # Nixpkgs
     nixpkgs = {
-      url = "github:nixos/nixpkgs/release-25.11";
+      # N.B. we use the nixos-x branch as this is updated *after* successful hydra builds
+      # rather than release-x. See https://wiki.nixos.org/wiki/Channel_branches
+      url = "github:nixos/nixpkgs/nixos-25.11";
     };
     nixpkgs-unstable = {
       url = "github:nixos/nixpkgs";
@@ -16,7 +18,6 @@
     flake-utils.url = "github:numtide/flake-utils";
     devshell = {
       url = "github:numtide/devshell";
-      inputs.flake-utils.follows = "flake-utils";
       inputs.nixpkgs.follows = "nixpkgs";
     };
   };
@@ -82,6 +83,11 @@
                       # level, so less duplication overall and no more fetching that 30MB src
                       # every time you run nix shell.
                       registry.nixpkgs.flake = inputs.nixpkgs;
+                      registry.nixpkgs-unstable.to = {
+                        owner = "nixos";
+                        repo = "nixpkgs";
+                        type = "github";
+                      };
                     };
                   }
                 )