diff --git a/modules/locale.nix b/modules/locale.nix
deleted file mode 100644
index 7764131d..00000000
--- a/modules/locale.nix
+++ /dev/null
@@ -1,4 +0,0 @@
-{
-  i18n.defaultLocale = "ja_JP.UTF-8";
-  i18n.supportedLocales = [ "ja_JP.UTF-8/UTF-8" "en_US.UTF-8/UTF-8" "fr_FR.UTF-8/UTF-8" ];
-}
diff --git a/modules/system.nix b/modules/system.nix
index f1322545..a70fd2e4 100644
--- a/modules/system.nix
+++ b/modules/system.nix
@@ -1,3 +1,8 @@
 {
+  time.timeZone = "America/New_York";
+
+  i18n.defaultLocale = "ja_JP.UTF-8";
+  i18n.supportedLocales = [ "ja_JP.UTF-8/UTF-8" "en_US.UTF-8/UTF-8" "fr_FR.UTF-8/UTF-8" ];
+
   system.stateVersion = "22.11";
 }
diff --git a/modules/timezone.nix b/modules/timezone.nix
deleted file mode 100644
index 5174a5b6..00000000
--- a/modules/timezone.nix
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  time.timeZone = "America/New_York";
-}