diff --git a/nixos/modules/services/misc/home-assistant.nix b/nixos/modules/services/misc/home-assistant.nix
index ac37c11106e..1dc7b44ee37 100644
--- a/nixos/modules/services/misc/home-assistant.nix
+++ b/nixos/modules/services/misc/home-assistant.nix
@@ -5,7 +5,10 @@ with lib;
 let
   cfg = config.services.home-assistant;
 
-  configFile = pkgs.writeText "configuration.yaml" (builtins.toJSON cfg.config);
+  # cfg.config != null can be assumed here
+  configFile = pkgs.writeText "configuration.json"
+    (builtins.toJSON (if cfg.applyDefaultConfig then
+    (lib.recursiveUpdate defaultConfig cfg.config) else cfg.config));
 
   availableComponents = pkgs.home-assistant.availableComponents;
 
@@ -38,6 +41,12 @@ let
     then (cfg.package.override { inherit extraComponents; })
     else cfg.package;
 
+  # If you are changing this, please update the description in applyDefaultConfig
+  defaultConfig = {
+    homeassistant.time_zone = config.time.timeZone;
+    http.server_port = (toString cfg.port);
+  };
+
 in {
   meta.maintainers = with maintainers; [ dotlambda ];
 
@@ -50,6 +59,26 @@ in {
       description = "The config directory, where your <filename>configuration.yaml</filename> is located.";
     };
 
+    port = mkOption {
+      default = 8123;
+      type = types.int;
+      description = "The port on which to listen.";
+    };
+
+    applyDefaultConfig = mkOption {
+      default = true;
+      type = types.bool;
+      description = ''
+        Setting this option enables a few configuration options for HA based on NixOS configuration (such as time zone) to avoid having to manually specify configuration we already have.
+        </para>
+        <para>
+        Currently one side effect of enabling this is that the <literal>http</literal> component will be enabled.
+        </para>
+        <para>
+        This only takes effect if <literal>config != null</literal> in order to ensure that a manually managed <filename>configuration.yaml</filename> is not overwritten.
+      '';
+    };
+
     config = mkOption {
       default = null;
       type = with types; nullOr attrs;
@@ -106,19 +135,20 @@ in {
       description = "Home Assistant";
       after = [ "network.target" ];
       preStart = lib.optionalString (cfg.config != null) ''
-        rm -f ${cfg.configDir}/configuration.yaml
-        ln -s ${configFile} ${cfg.configDir}/configuration.yaml
+        config=${cfg.configDir}/configuration.yaml
+        rm -f $config
+        ${pkgs.remarshal}/bin/json2yaml -i ${configFile} -o $config
+        chmod 444 $config
       '';
       serviceConfig = {
-        ExecStart = ''
-          ${package}/bin/hass --config "${cfg.configDir}"
-        '';
+        ExecStart = "${package}/bin/hass --config '${cfg.configDir}'";
         User = "hass";
         Group = "hass";
         Restart = "on-failure";
         ProtectSystem = "strict";
         ReadWritePaths = "${cfg.configDir}";
         PrivateTmp = true;
+        RemoveIPC = true;
       };
       path = [
         "/run/wrappers" # needed for ping
diff --git a/nixos/tests/home-assistant.nix b/nixos/tests/home-assistant.nix
index 2e45dc78471..4ebccb7ab86 100644
--- a/nixos/tests/home-assistant.nix
+++ b/nixos/tests/home-assistant.nix
@@ -51,9 +51,9 @@ in {
     startAll;
     $hass->waitForUnit("home-assistant.service");
 
-    # Since config is specified using a Nix attribute set,
-    # configuration.yaml is a link to the Nix store
-    $hass->succeed("test -L ${configDir}/configuration.yaml");
+    # The config is specified using a Nix attribute set,
+    # but then converted from JSON to YAML
+    $hass->succeed("test -f ${configDir}/configuration.yaml");
 
     # Check that Home Assistant's web interface and API can be reached
     $hass->waitForOpenPort(8123);
diff --git a/pkgs/development/tools/remarshal/default.nix b/pkgs/development/tools/remarshal/default.nix
index baba4fd75ea..23c9768f7e0 100644
--- a/pkgs/development/tools/remarshal/default.nix
+++ b/pkgs/development/tools/remarshal/default.nix
@@ -1,7 +1,7 @@
-{ stdenv, pythonPackages, fetchFromGitHub }:
+{ stdenv, python3Packages, fetchFromGitHub }:
 
-pythonPackages.buildPythonApplication rec {
-  name = "remarshal-${version}";
+python3Packages.buildPythonApplication rec {
+  pname = "remarshal";
   version = "0.7.0";
 
   src = fetchFromGitHub {
@@ -11,10 +11,8 @@ pythonPackages.buildPythonApplication rec {
     sha256 = "1wsgvzfp40lvly7nyyhv9prip4vi32rfc8kdji587jpw28zc1dfb";
   };
 
-  propagatedBuildInputs = with pythonPackages; [
-    dateutil
-    pytoml
-    pyyaml
+  propagatedBuildInputs = with python3Packages; [
+    dateutil pytoml pyyaml
   ];
 
   meta = with stdenv.lib; {