diff --git a/modules/security/sudo.nix b/modules/security/sudo.nix
index 76c325d8d8f..e3e463e155f 100644
--- a/modules/security/sudo.nix
+++ b/modules/security/sudo.nix
@@ -34,6 +34,7 @@ in
 
           # Environment variables to keep for root and %wheel.
           Defaults:root,%wheel env_keep+=LOCALE_ARCHIVE
+          Defaults:root,%wheel env_keep+=NIX_CONF_DIR
           Defaults:root,%wheel env_keep+=NIX_PATH
           Defaults:root,%wheel env_keep+=TERMINFO_DIRS