diff --git a/.github/workflows/tag.yaml b/.github/workflows/tag.yaml
index 768e1878..38c0d0d1 100644
--- a/.github/workflows/tag.yaml
+++ b/.github/workflows/tag.yaml
@@ -50,7 +50,11 @@ jobs:
     - name: Update version and vendor hashes in Nix derivation
       id: nix-update-hashes
       run: |
-        nix develop .#ci --command nix-update --flake --version ${{ steps.tags.outputs.next || steps.tags.outputs.current }} default
+        alias nix-update="nix develop .#ci --command nix-update --flake --version ${{ steps.tags.outputs.next || steps.tags.outputs.current }}"
+
+        nix-update gocov-merger
+        nix-update cunicu
+
         git diff --quiet || echo "changed=true" >> "$GITHUB_OUTPUT"
 
     - name: Commit changes
diff --git a/flake.lock b/flake.lock
index 45c34f95..f1896f6e 100644
--- a/flake.lock
+++ b/flake.lock
@@ -18,13 +18,37 @@
         "type": "github"
       }
     },
+    "nix-update": {
+      "inputs": {
+        "flake-parts": [
+          "flake-parts"
+        ],
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "treefmt-nix": "treefmt-nix"
+      },
+      "locked": {
+        "lastModified": 1734774211,
+        "narHash": "sha256-C3xQn5oG2HIFM3ITncfsfPMqnRhBIx1+At1GKDV9CxM=",
+        "owner": "Mic92",
+        "repo": "nix-update",
+        "rev": "33baee51bcf3bf20271d812c7b8922d776cc764f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "Mic92",
+        "repo": "nix-update",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1734435836,
-        "narHash": "sha256-kMBQ5PRiFLagltK0sH+08aiNt3zGERC2297iB6vrvlU=",
+        "lastModified": 1735821806,
+        "narHash": "sha256-cuNapx/uQeCgeuhUhdck3JKbgpsml259sjUQnWM7zW8=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "4989a246d7a390a859852baddb1013f825435cee",
+        "rev": "d6973081434f88088e5321f83ebafe9a1167c367",
         "type": "github"
       },
       "original": {
@@ -49,8 +73,30 @@
     "root": {
       "inputs": {
         "flake-parts": "flake-parts",
+        "nix-update": "nix-update",
         "nixpkgs": "nixpkgs"
       }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nix-update",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1730321837,
+        "narHash": "sha256-vK+a09qq19QNu2MlLcvN4qcRctJbqWkX7ahgPZ/+maI=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "746901bb8dba96d154b66492a29f5db0693dbfcc",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
     }
   },
   "root": "root",
diff --git a/flake.nix b/flake.nix
index a6754cf9..6c430790 100644
--- a/flake.nix
+++ b/flake.nix
@@ -5,15 +5,18 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
     flake-parts.url = "github:hercules-ci/flake-parts";
+    nix-update = {
+      url = "github:Mic92/nix-update";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+        flake-parts.follows = "flake-parts";
+      };
+    };
   };
 
   outputs =
-    inputs@{
-      nixpkgs,
-      self,
-      flake-parts,
-    }:
-    flake-parts.lib.mkFlake { inherit inputs; } {
+    inputs@{ self, ... }:
+    inputs.flake-parts.lib.mkFlake { inherit inputs; } {
       flake = {
         nixosModules = rec {
           default = cunicu;
@@ -21,7 +24,10 @@
         };
 
         overlays = {
-          default = final: prev: { cunicu = final.callPackage ./nix/cunicu.nix { }; };
+          default = final: prev: {
+            cunicu = final.callPackage ./nix/cunicu.nix { };
+            gocov-merger = final.callPackage ./nix/gocov-merger.nix { };
+          };
         };
       };
 
@@ -39,7 +45,7 @@
           ...
         }:
         let
-          pkgs = import nixpkgs {
+          pkgs = import inputs.nixpkgs {
             inherit system;
             overlays = [ self.overlays.default ];
           };
@@ -47,13 +53,17 @@
         {
           formatter = pkgs.nixfmt-rfc-style;
 
-          devShells = {
-            default = import ./nix/shell.nix { inherit pkgs self'; };
-            ci = import ./nix/shell-ci.nix { inherit pkgs; };
-          };
+          devShells =
+            let
+              inherit (inputs.nix-update.packages.${system}) nix-update;
+            in
+            {
+              default = pkgs.callPackage ./nix/shell.nix { inherit nix-update; };
+              ci = pkgs.callPackage ./nix/shell-ci.nix { inherit nix-update; };
+            };
 
           packages = {
-            inherit (pkgs) cunicu;
+            inherit (pkgs) cunicu gocov-merger;
 
             default = pkgs.cunicu;
           };
diff --git a/nix/gocov-merger.nix b/nix/gocov-merger.nix
new file mode 100644
index 00000000..5c74fe06
--- /dev/null
+++ b/nix/gocov-merger.nix
@@ -0,0 +1,27 @@
+# SPDX-FileCopyrightText: 2025 Steffen Vogel <post@steffenvogel.de>
+# SPDX-License-Identifier: Apache-2.0
+{
+  lib,
+  buildGoModule,
+  fetchFromGitHub,
+}:
+buildGoModule {
+  pname = "gocov-merger";
+  version = "0.10.0";
+
+  src = fetchFromGitHub {
+    owner = "amobe";
+    repo = "gocov-merger";
+    rev = "5494981677165bdf08c8c0595c3b6ed246cb77de";
+    hash = "sha256-zec5gKWbZBAIqlxRS811AwSZxNjmbIsE5/zInp94kR8=";
+  };
+
+  vendorHash = "sha256-6DznXSmQkb91GJZ2WMAIg558y+8a46KjRKfWRHsvus0=";
+
+  meta = {
+    description = "Merge coverprofile results from multiple go cover runs";
+    homepage = "https://github.com/amobe/gocov-merger";
+    license = lib.licenses.bsd2;
+    maintainers = with lib.maintainers; [ stv0g ];
+  };
+}
diff --git a/nix/shell-ci.nix b/nix/shell-ci.nix
index c984b7fc..882d1c1e 100644
--- a/nix/shell-ci.nix
+++ b/nix/shell-ci.nix
@@ -1,8 +1,14 @@
 # SPDX-FileCopyrightText: 2023 Philipp Jungkamp <p.jungkamp@gmx.net>
 # SPDX-License-Identifier: Apache-2.0
-{ pkgs, ... }:
-pkgs.mkShell {
-  packages = with pkgs; [
+{
+  mkShell,
+
+  nix-update,
+  goreleaser,
+  svu,
+}:
+mkShell {
+  packages = [
     nix-update
     goreleaser
     svu
diff --git a/nix/shell.nix b/nix/shell.nix
index b65f40d2..7106cd2b 100644
--- a/nix/shell.nix
+++ b/nix/shell.nix
@@ -1,42 +1,46 @@
 # SPDX-FileCopyrightText: 2023 Philipp Jungkamp <p.jungkamp@gmx.net>
 # SPDX-FileCopyrightText: 2025 Steffen Vogel <post@steffenvogel.de>
 # SPDX-License-Identifier: Apache-2.0
-{ self', pkgs, ... }:
-pkgs.mkShell {
-  packages = with pkgs; [
-    yarn-berry
-    protobuf
-    gnumake
-    libpcap
-    reuse
-    ginkgo
-    goreleaser
-    golangci-lint
-    protoc-gen-go
-    protoc-gen-go-grpc
-    evans
+{
+  mkShell,
 
-    nix-update
-    goreleaser
-    svu
-
-    (buildGoModule {
-      name = "gocov-merger";
-
-      src = fetchFromGitHub {
-        owner = "amobe";
-        repo = "gocov-merger";
-        rev = "5494981677165bdf08c8c0595c3b6ed246cb77de";
-        hash = "sha256-zec5gKWbZBAIqlxRS811AwSZxNjmbIsE5/zInp94kR8=";
-      };
-
-      vendorHash = "sha256-6DznXSmQkb91GJZ2WMAIg558y+8a46KjRKfWRHsvus0=";
-    })
+  coturn,
+  cunicu,
+  cunicu-website,
+  evans,
+  ginkgo,
+  gnumake,
+  gocov-merger,
+  golangci-lint,
+  goreleaser,
+  inotify-tools,
+  libpcap,
+  nix-update,
+  reuse,
+  svu,
 
+  ...
+}:
+mkShell {
+  packages = [
     coturn
+    evans
+    ginkgo
+    gnumake
+    gocov-merger
+    golangci-lint
+    goreleaser
+    inotify-tools
+    libpcap
+    nix-update
+    reuse
+    svu
   ];
 
-  inputsFrom = [ self'.packages.cunicu ];
+  inputsFrom = [
+    cunicu
+    cunicu-website
+  ];
 
   hardeningDisable = [ "fortify" ];
 }