diff --git a/configuration.nix b/configuration.nix
index 84d5af2..2bab3cf 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -42,6 +42,7 @@
   ];
 
   # Define a user account.
+  users.mutableUsers = false;
   users.users.root = {
     hashedPassword = lib.fileContents ./secrets/shadow-hashed-password-root;
   };