diff --git a/hosts/pi-server/default.nix b/hosts/pi-server/default.nix
index c2f6ea9..eb53d34 100644
--- a/hosts/pi-server/default.nix
+++ b/hosts/pi-server/default.nix
@@ -44,7 +44,7 @@ in {
 
   # Select internationalisation properties.
   i18n = {
-    defaultLocale = "en_US.utf8";
+    defaultLocale = "en_US.UTF-8";
     inputMethod = {
       enable = true;
       type = "fcitx5";
diff --git a/hosts/server/default.nix b/hosts/server/default.nix
index 3ba56c1..f43a759 100644
--- a/hosts/server/default.nix
+++ b/hosts/server/default.nix
@@ -44,7 +44,7 @@ in {
 
   # Select internationalisation properties.
   i18n = {
-    defaultLocale = "en_US.utf8";
+    defaultLocale = "en_US.UTF-8";
     inputMethod = {
       enable = true;
       type = "fcitx5";
diff --git a/hosts/workstation/default.nix b/hosts/workstation/default.nix
index 798b5e7..439f609 100644
--- a/hosts/workstation/default.nix
+++ b/hosts/workstation/default.nix
@@ -85,7 +85,7 @@ in {
 
   # Select internationalisation properties.
   i18n = {
-    defaultLocale = "en_US.utf8";
+    defaultLocale = "en_US.UTF-8";
     inputMethod = {
       enable = true;
       type = "fcitx5";