diff --git a/modules/system/boot/luksroot.nix b/modules/system/boot/luksroot.nix
index 9a2ef7860634..7f9898770a98 100644
--- a/modules/system/boot/luksroot.nix
+++ b/modules/system/boot/luksroot.nix
@@ -63,7 +63,7 @@ in
         device = mkOption {
           example = "/dev/sda2";
           type = types.string;
-          description = "Path of the underlying block device."
+          description = "Path of the underlying block device.";
         };
 
         preLVM = mkOption {