diff --git a/flake.nix b/flake.nix
index f0eb8ab..404cc42 100644
--- a/flake.nix
+++ b/flake.nix
@@ -46,7 +46,7 @@
 
   outputs = { self, nixpkgs, nixos-hardware, flake-utils, home-manager, nur
     , neovim, obelisk, photoprism-flake, pre-commit-hooks, nvim-ts-autotag
-    , nvim-ts-context-commentstring }:
+    , nvim-ts-context-commentstring }@inputs:
     let
       overlays = {
         neovim = self: super:
@@ -78,43 +78,58 @@
           photoprism = photoprism-flake.defaultPackage.${self.system};
         };
       };
-      systemModule = { hostName, hardwareConfig, config }:
-        ({ pkgs, ... }: {
-          networking.hostName = hostName;
+      nixosModules = { flakeDefaults = import ./modules/flakeDefaults.nix; };
+      homeManagerModules = { git = import ./home/modules/git.nix; };
+      systemDefaults = {
+        modules = [ nixosModules.flakeDefaults ];
+        overlays = [
+          nur.overlay
+          overlays.wayland
+          overlays.neovim
+          overlays.deconz
+          overlays.photoprism
+          overlays.obelisk
+        ];
+      };
+      lib = rec {
+        createSystem = hostName:
+          { hardwareConfig, config }:
+          ({ pkgs, lib, ... }: {
+            networking.hostName = hostName;
 
-          # Let 'nixos-version --json' know about the Git revision
-          # of this flake.
-          system.configurationRevision = nixpkgs.lib.mkIf (self ? rev) self.rev;
+            nixpkgs.overlays = systemDefaults.overlays;
 
-          nix.registry.nixpkgs.flake = nixpkgs;
-
-          nixpkgs.overlays = [
-            nur.overlay
-            overlays.neovim
-            overlays.deconz
-            overlays.photoprism
-            overlays.obelisk
-          ];
-
-          imports =
-            [ hardwareConfig home-manager.nixosModules.home-manager config ];
-        });
+            imports = systemDefaults.modules ++ [
+              hardwareConfig
+              config
+              {
+                # make arguments available to modules
+                _module.args = { inherit self inputs; };
+              }
+            ];
+          });
+        createUser' = import ./lib/createUser.nix;
+        createUser = name: args:
+          ({ pkgs, ... }@args2:
+            (createUser' name args) ({ inherit home-manager; } // args2));
+      };
     in rec {
 
-      inherit overlays;
-
-      homeManagerModules.git = import ./home/modules/git.nix;
+      inherit lib overlays nixosModules homeManagerModules;
 
       nixosConfigurations.felix-nixos = nixpkgs.lib.nixosSystem {
         system = "x86_64-linux";
         modules = [
           nixpkgs.nixosModules.notDetected
-          { home-manager.users.felschr.imports = [ homeManagerModules.git ]; }
-          (systemModule {
-            hostName = "felix-nixos";
+          (lib.createSystem "felix-nixos" {
             hardwareConfig = ./hardware/felix-nixos.nix;
             config = ./home-pc.nix;
           })
+          (lib.createUser "felschr" {
+            user.extraGroups = [ "wheel" "audio" "docker" "disk" ];
+            modules = [ homeManagerModules.git ];
+            config = ./home/felschr.nix;
+          })
         ];
       };
 
@@ -122,12 +137,15 @@
         system = "x86_64-linux";
         modules = [
           nixpkgs.nixosModules.notDetected
-          { home-manager.users.felschr.imports = [ homeManagerModules.git ]; }
-          (systemModule {
-            hostName = "pilot1";
+          (lib.createSystem "pilot1" {
             hardwareConfig = ./hardware-configuration.nix; # TODO
             config = ./work-pc.nix;
           })
+          (lib.createUser "felschr" {
+            user.extraGroups = [ "wheel" "audio" "docker" "disk" ];
+            modules = [ homeManagerModules.git ];
+            config = ./home/felschr-work.nix;
+          })
         ];
       };
 
@@ -136,15 +154,19 @@
         modules = [
           nixpkgs.nixosModules.notDetected
           nixos-hardware.nixosModules.raspberry-pi-4
-          {
-            home-manager.users.felschr.imports = [ homeManagerModules.git ];
-          }
           # photoprism-flake.nixosModules.photoprism
-          (systemModule {
-            hostName = "felix-rpi4";
+          (lib.createSystem "felix-rpi4" {
             hardwareConfig = ./hardware/rpi4.nix;
             config = ./rpi4.nix;
           })
+          (lib.createUser "felschr" {
+            user = {
+              extraGroups = [ "wheel" "audio" "disk" "media" ];
+              openssh.authorizedKeys.keyFiles = [ ./key ];
+            };
+            modules = [ homeManagerModules.git ];
+            config = ./home/felschr-rpi4.nix;
+          })
         ];
       };
 
diff --git a/home-pc.nix b/home-pc.nix
index c12bad3..c716d85 100644
--- a/home-pc.nix
+++ b/home-pc.nix
@@ -44,19 +44,6 @@
 
   services.printing.drivers = with pkgs; [ epson-escpr ];
 
-  users.users.felschr = {
-    isNormalUser = true;
-    extraGroups = [ "wheel" "audio" "docker" "disk" ];
-    shell = pkgs.zsh;
-  };
-
-  home-manager = {
-    useUserPackages = true;
-    useGlobalPkgs = true;
-    backupFileExtension = "backup";
-    users.felschr = import ./home/felschr.nix;
-  };
-
   # only change this when specified in release notes
   system.stateVersion = "21.05";
 }
diff --git a/lib/createUser.nix b/lib/createUser.nix
new file mode 100644
index 0000000..dfecec0
--- /dev/null
+++ b/lib/createUser.nix
@@ -0,0 +1,18 @@
+name:
+{ user ? { }, hm ? { }, modules ? [ ], config, ... }:
+
+{ pkgs, lib, home-manager, ... }: {
+  imports = [ home-manager.nixosModules.home-manager ];
+
+  users.users."${name}" = {
+    isNormalUser = true;
+    shell = pkgs.zsh;
+  } // user;
+
+  home-manager = {
+    useUserPackages = true;
+    useGlobalPkgs = true;
+    backupFileExtension = "backup";
+    users."${name}" = lib.mkMerge [ { imports = modules; } (import config) ];
+  } // hm;
+}
diff --git a/modules/flakeDefaults.nix b/modules/flakeDefaults.nix
new file mode 100644
index 0000000..fd78913
--- /dev/null
+++ b/modules/flakeDefaults.nix
@@ -0,0 +1,17 @@
+{ pkgs, lib, self, inputs, ... }:
+
+let
+  flakes = lib.filterAttrs (name: value: value ? outputs) inputs;
+  nixRegistry = builtins.mapAttrs (name: v: { flake = v; }) flakes;
+in {
+  # Let 'nixos-version --json' know about the Git revision
+  # of this flake.
+  system.configurationRevision = lib.mkIf (self ? rev) self.rev;
+
+  nix = {
+    extraOptions = "experimental-features = nix-command flakes";
+    nixPath = lib.mapAttrsToList (n: v: "${n}=${v}") flakes;
+    registry = nixRegistry;
+    package = pkgs.nixUnstable;
+  };
+}
diff --git a/rpi4.nix b/rpi4.nix
index ffbfa8e..ccc2ea3 100644
--- a/rpi4.nix
+++ b/rpi4.nix
@@ -85,20 +85,6 @@ with builtins; {
     authorizedKeys = [ (readFile "./key") ];
   };
 
-  users.users.felschr = {
-    isNormalUser = true;
-    extraGroups = [ "wheel" "audio" "disk" "media" ];
-    shell = pkgs.zsh;
-    openssh.authorizedKeys.keyFiles = [ ./key ];
-  };
-
-  home-manager = {
-    useUserPackages = true;
-    useGlobalPkgs = true;
-    backupFileExtension = "backup";
-    users.felschr = import ./home/felschr-rpi4.nix;
-  };
-
   # only change this when specified in release notes
   system.stateVersion = "21.05";
 }
diff --git a/work-pc.nix b/work-pc.nix
index 44fc5d9..9c7d23b 100644
--- a/work-pc.nix
+++ b/work-pc.nix
@@ -32,19 +32,6 @@
 
   services.printing.drivers = with pkgs; [ epson-escpr ];
 
-  users.users.felschr = {
-    isNormalUser = true;
-    extraGroups = [ "wheel" "audio" "docker" "disk" ];
-    shell = pkgs.zsh;
-  };
-
-  home-manager = {
-    useUserPackages = true;
-    useGlobalPkgs = true;
-    backupFileExtension = "backup";
-    users.felschr = import ./home/felschr-work.nix;
-  };
-
   # only change this when specified in release notes
   system.stateVersion = "21.05";
 }