diff --git a/configs/all-configurations.nix b/configs/all-configurations.nix
index 5a404aae9..56fa61143 100644
--- a/configs/all-configurations.nix
+++ b/configs/all-configurations.nix
@@ -1,3 +1,3 @@
-{ pkgs }: {
+{pkgs}: {
   liberaforms-container = import ./liberaforms/container.nix;
 }
diff --git a/flake.nix b/flake.nix
index a8f3004c7..0584c0620 100644
--- a/flake.nix
+++ b/flake.nix
@@ -9,58 +9,64 @@
   inputs.treefmt-nix.url = "github:numtide/treefmt-nix";
   inputs.treefmt-nix.inputs.nixpkgs.follows = "nixpkgs";
 
-  outputs = inputs@{ self, nixpkgs, flake-utils, treefmt-nix, ... }:
-    let
-      buildOutputs = system:
-        let
-          pkgs = nixpkgs.legacyPackages.${system};
-          treefmtEval = treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
-        in {
-          packages = import ./all-packages.nix { inherit (pkgs) newScope; };
-          nixosModules = {
-            modules = import ./modules/all-modules.nix;
-            ngipkgs = { ... }: {
-              # Inject an additional argument into the module system evaluation.
-              # This way our package set can be accessed separately and we don't have
-              # to muck around with overlays (which don't work with flakes as you'd expect)
-              _module.args.ngipkgs = self.packages.${system};
-            };
-          };
-
-          formatter = treefmtEval.config.build.wrapper;
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+    treefmt-nix,
+    ...
+  }: let
+    buildOutputs = system: let
+      pkgs = nixpkgs.legacyPackages.${system};
+      treefmtEval = treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
+    in {
+      packages = import ./all-packages.nix {inherit (pkgs) newScope;};
+      nixosModules = {
+        modules = import ./modules/all-modules.nix;
+        ngipkgs = {...}: {
+          # Inject an additional argument into the module system evaluation.
+          # This way our package set can be accessed separately and we don't have
+          # to muck around with overlays (which don't work with flakes as you'd expect)
+          _module.args.ngipkgs = self.packages.${system};
         };
+      };
 
-      checkOutputs = system:
-        let
-          pkgs = nixpkgs.legacyPackages.${system};
-          treefmtEval = treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
-          inject-ngipkgs = k: v:
-            pkgs.nixos
-            ({ ... }: { imports = [ self.nixosModules.${system}.ngipkgs v ]; });
-
-          ngipkgsModule = self.nixosModules.${system}.ngipkgs;
-        in {
-          # Configurations have to go in checkOutputs (ie, avoid `eachDefaultSystem`) to generate
-          # a single attribute name for nixos-container deployments (`<config-name>`), because
-          # nixos-container can't parse dot-separated sequence attribute paths (`x86_64-linux.<config-name>`).
-          nixosConfigurations = let
-            all-configurations =
-              import ./configs/all-configurations.nix { inherit pkgs; };
-          in builtins.mapAttrs inject-ngipkgs all-configurations;
+      formatter = treefmtEval.config.build.wrapper;
+    };
 
-          # To generate a Hydra jobset for CI builds of all packages
-          # https://hydra.ngi0.nixos.org/jobset/ngipkgs/main
-          hydraJobs = { packages.${system} = self.packages.${system}; };
+    checkOutputs = system: let
+      pkgs = nixpkgs.legacyPackages.${system};
+      treefmtEval = treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
+      ngipkgsModule = self.nixosModules.${system}.ngipkgs;
+    in {
+      # Configurations have to go in checkOutputs (ie, avoid `eachDefaultSystem`) to generate
+      # a single attribute name for nixos-container deployments (`<config-name>`), because
+      # nixos-container can't parse dot-separated sequence attribute paths (`x86_64-linux.<config-name>`).
+      nixosConfigurations = let
+        all-configurations = import ./configs/all-configurations.nix {inherit pkgs;};
+        inject-ngipkgs = k: v: pkgs.nixos ({...}: {imports = [ngipkgsModule v];});
+      in
+        builtins.mapAttrs inject-ngipkgs all-configurations;
 
-          test-pretalx = pkgs.nixosTest
-            (import ./tests/pretalx/pretalx.nix { inherit ngipkgsModule;});
+      # To generate a Hydra jobset for CI builds of all packages
+      # https://hydra.ngi0.nixos.org/jobset/ngipkgs/main
+      hydraJobs = {
+        packages.${system} = self.packages.${system};
+      };
 
-          # For .github/workflows/ci.yaml to *build* all packages, because
-          # `nix flake check` only evaluates packages, but it builds checks.
-          checks.${system} = self.packages.${system} // {
-            formatting = treefmtEval.config.build.check self;
-          };
+      # For .github/workflows/ci.yaml to *build* all packages, because
+      # `nix flake check` only evaluates packages, but it builds checks.
+      checks.${system} =
+        self.packages.${system}
+        // {
+          formatting = treefmtEval.config.build.check self;
+          test-pretalx =
+            pkgs.nixosTest
+            (import ./tests/pretalx/pretalx.nix {
+              inherit ngipkgsModule;
+            });
         };
-    in (flake-utils.lib.eachDefaultSystem buildOutputs)
-    // (checkOutputs "x86_64-linux");
+    };
+  in
+    (flake-utils.lib.eachDefaultSystem buildOutputs) // (checkOutputs "x86_64-linux");
 }
diff --git a/modules/pretalx.nix b/modules/pretalx.nix
index ebee1de91..559947ac6 100644
--- a/modules/pretalx.nix
+++ b/modules/pretalx.nix
@@ -1,6 +1,11 @@
-{ config, lib, pkgs, ngipkgs, ... }:
-with lib;
-let
+{
+  config,
+  lib,
+  pkgs,
+  ngipkgs,
+  ...
+}:
+with lib; let
   cfg = config.services.pretalx;
   group = "pretalx";
   default_home = "/var/lib/pretalx";
@@ -20,26 +25,30 @@ let
     port = "8001";
   };
 
-  environmentFile = pkgs.runCommand "pretalx-environ" {
-    buildInputs = [ pretalx gunicorn ];  # Sets PYTHONPATH in derivation
-  } ''
-    cat > $out <<EOF
-    PYTHONPATH=$PYTHONPATH
-    EOF
-  '';
-
-  mkTimer = { description, unit, onCalendar }: {
+  environmentFile =
+    pkgs.runCommand "pretalx-environ" {
+      buildInputs = [pretalx gunicorn]; # Sets PYTHONPATH in derivation
+    } ''
+      cat > $out <<EOF
+      PYTHONPATH=$PYTHONPATH
+      EOF
+    '';
+
+  mkTimer = {
+    description,
+    unit,
+    onCalendar,
+  }: {
     inherit description;
-    requires = [ "pretalx-migrate.service" ];
-    after = [ "network.target" ];
-    wantedBy = [ "timers.target" ];
+    requires = ["pretalx-migrate.service"];
+    after = ["network.target"];
+    wantedBy = ["timers.target"];
     timerConfig = {
       Persistent = true;
       OnCalendar = onCalendar;
       Unit = unit;
     };
   };
-
 in {
   options.services.pretalx = with types; {
     enable = mkEnableOption "pretalx server";
@@ -115,9 +124,9 @@ in {
           --bind=${server.bind}:${server.port}
         '';
       };
-      wantedBy = [ "multi-user.target" ];
-      requires = [ "pretalx-migrate.service" ];
-      after = [ "network.target" ];
+      wantedBy = ["multi-user.target"];
+      requires = ["pretalx-migrate.service"];
+      after = ["network.target"];
     };
 
     systemd.services.pretalx-clearsessions = {
diff --git a/pkgs/pretalx/default.nix b/pkgs/pretalx/default.nix
index 6ee6b6e84..d52fe0323 100644
--- a/pkgs/pretalx/default.nix
+++ b/pkgs/pretalx/default.nix
@@ -1,42 +1,47 @@
-{ lib, fetchFromGitHub, gettext, poetry2nix }:
-let
+{
+  lib,
+  fetchFromGitHub,
+  gettext,
+  poetry2nix,
+}: let
   pname = "pretalx";
   version = "v2.3.2";
 in (poetry2nix.mkPoetryApplication {
   projectDir = ./.;
-  propagatedBuildInputs = [ gettext ];
+  propagatedBuildInputs = [gettext];
 
-  overrides = poetry2nix.overrides.withDefaults (self: super:
-    let
-      f = (old: {
-        propagatedBuildInputs = (old.propagatedBuildInputs or [ ])
-          ++ [ self.setuptools ];
-      });
-    in {
-      defusedcsv = super.defusedcsv.overridePythonAttrs f;
-      django-context-decorator =
-        super.django-context-decorator.overridePythonAttrs f;
-      django-i18nfield = super.django-i18nfield.overridePythonAttrs f;
-      publicsuffixlist = super.publicsuffixlist.overridePythonAttrs f;
-      rules = super.rules.overridePythonAttrs f;
-      urlman = super.urlman.overridePythonAttrs f;
-      kombu = super.kombu.overridePythonAttrs
-        (old: (f old) // { patches = [ ./kombu.patch ]; });
-      celery = super.celery.overridePythonAttrs
-        (old: { patches = [ ./celery.patch ]; });
-      django-hierarkey = super.django-hierarkey.overridePythonAttrs f;
-      django-jquery-js = super.django-jquery-js.overridePythonAttrs f;
-      django-scopes = super.django-scopes.overridePythonAttrs f;
-      django-bootstrap4 = super.django-bootstrap4.overridePythonAttrs f;
-      inlinestyler = super.inlinestyler.overridePythonAttrs f;
-      django-libsass = super.django-libsass.overridePythonAttrs f;
-    });
+  overrides = poetry2nix.overrides.withDefaults (self: super: let
+    f = old: {
+      propagatedBuildInputs =
+        (old.propagatedBuildInputs or [])
+        ++ [self.setuptools];
+    };
+  in {
+    defusedcsv = super.defusedcsv.overridePythonAttrs f;
+    django-context-decorator =
+      super.django-context-decorator.overridePythonAttrs f;
+    django-i18nfield = super.django-i18nfield.overridePythonAttrs f;
+    publicsuffixlist = super.publicsuffixlist.overridePythonAttrs f;
+    rules = super.rules.overridePythonAttrs f;
+    urlman = super.urlman.overridePythonAttrs f;
+    kombu =
+      super.kombu.overridePythonAttrs
+      (old: (f old) // {patches = [./kombu.patch];});
+    celery =
+      super.celery.overridePythonAttrs
+      (old: {patches = [./celery.patch];});
+    django-hierarkey = super.django-hierarkey.overridePythonAttrs f;
+    django-jquery-js = super.django-jquery-js.overridePythonAttrs f;
+    django-scopes = super.django-scopes.overridePythonAttrs f;
+    django-bootstrap4 = super.django-bootstrap4.overridePythonAttrs f;
+    inlinestyler = super.inlinestyler.overridePythonAttrs f;
+    django-libsass = super.django-libsass.overridePythonAttrs f;
+  });
 
   meta = with lib; {
     description = pname;
     homepage = "https://example.com";
     license = licenses.unlicense;
-    maintainers = [ ];
+    maintainers = [];
   };
 })
-
diff --git a/tests/pretalx/pretalx.nix b/tests/pretalx/pretalx.nix
index fd0bfcd06..53e5810d3 100644
--- a/tests/pretalx/pretalx.nix
+++ b/tests/pretalx/pretalx.nix
@@ -1,14 +1,14 @@
-{ ngipkgsModule, ... }: {
+{ngipkgsModule, ...}: {
   name = "pretalx tests";
 
   nodes = {
     server = {
-      imports = [ 
+      imports = [
         ../../modules/pretalx.nix
         ngipkgsModule
       ];
 
-      networking.firewall.allowedTCPPorts = [ 8001 ];
+      networking.firewall.allowedTCPPorts = [8001];
 
       services.pretalx = {
         enable = true;
@@ -52,7 +52,7 @@
     };
   };
 
-  testScript = { nodes, ... }: ''
+  testScript = {nodes, ...}: ''
     start_all()
 
     with subtest("Test http service"):