diff --git a/nix-darwin/default.nix b/nix-darwin/default.nix
index 956695926..c529ca4a1 100644
--- a/nix-darwin/default.nix
+++ b/nix-darwin/default.nix
@@ -9,7 +9,10 @@ let
   extendedLib = import ../modules/lib/stdlib-extended.nix pkgs.lib;
 
   hmModule = types.submoduleWith {
-    specialArgs = { lib = extendedLib; };
+    specialArgs = { 
+      lib = extendedLib; 
+      darwinConfig = config;
+    } // cfg.extraSpecialArgs;
     modules = [
       ({ name, ... }: {
         imports = import ../modules/modules.nix {
@@ -26,7 +29,7 @@ let
           home.homeDirectory = config.users.users.${name}.home;
         };
       })
-    ];
+    ] ++ cfg.sharedModules;
   };
 
 in
@@ -55,6 +58,24 @@ in
         '';
       };
 
+      extraSpecialArgs = mkOption {
+        type = types.attrs;
+        default = { };
+        example = literalExample "{ modulesPath = ../modules; }";
+        description = ''
+          Extra <literal>specialArgs</literal> passed to Home Manager.
+        '';
+      };
+
+      sharedModules = mkOption {
+        type = with types; listOf (oneOf [ attrs (functionTo attrs) path ]);
+        default = [ ];
+        example = literalExample "[ { home.packages = [ nixpkgs-fmt ]; } ]";
+        description = ''
+          Extra modules added to all users.
+        '';
+      };
+
       verbose = mkEnableOption "verbose output on activation";
 
       users = mkOption {
diff --git a/nixos/default.nix b/nixos/default.nix
index 6645b9068..4b58d154c 100644
--- a/nixos/default.nix
+++ b/nixos/default.nix
@@ -12,7 +12,7 @@ let
     specialArgs = {
       lib = extendedLib;
       nixosConfig = config;
-    };
+    } // cfg.extraSpecialArgs;
     modules = [
       ({ name, ... }: {
         imports = import ../modules/modules.nix {
@@ -34,7 +34,7 @@ let
           home.homeDirectory = config.users.users.${name}.home;
         };
       })
-    ];
+    ] ++ cfg.sharedModules;
   };
 
   serviceEnvironment = optionalAttrs (cfg.backupFileExtension != null) {
@@ -65,6 +65,24 @@ in {
         '';
       };
 
+      extraSpecialArgs = mkOption {
+        type = types.attrs;
+        default = { };
+        example = literalExample "{ modulesPath = ../modules; }";
+        description = ''
+          Extra <literal>specialArgs</literal> passed to Home Manager.
+        '';
+      };
+
+      sharedModules = mkOption {
+        type = with types; listOf (oneOf [ attrs (functionTo attrs) path ]);
+        default = [ ];
+        example = literalExample "[ { home.packages = [ nixpkgs-fmt ]; } ]";
+        description = ''
+          Extra modules added to all users.
+        '';
+      };
+
       verbose = mkEnableOption "verbose output on activation";
 
       users = mkOption {