diff --git a/modules/system/boot/stage-1.nix b/modules/system/boot/stage-1.nix
index 440255f6f6cc..75f83a27db9d 100644
--- a/modules/system/boot/stage-1.nix
+++ b/modules/system/boot/stage-1.nix
@@ -304,7 +304,7 @@ let
 
     # !!! copy&pasted from upstart-jobs/filesystems.nix.
     mountPoints =
-      if fileSystems == null
+      if fileSystems == []
       then abort "You must specify the fileSystems option!"
       else map (fs: fs.mountPoint) fileSystems;
     devices = map (fs: if fs.device != null then fs.device else "/dev/disk/by-label/${fs.label}") fileSystems;
diff --git a/modules/tasks/filesystems.nix b/modules/tasks/filesystems.nix
index 557c5873d944..efa07d35ddc7 100644
--- a/modules/tasks/filesystems.nix
+++ b/modules/tasks/filesystems.nix
@@ -69,7 +69,7 @@ in
         <command>mkdir -p</command> .
       '';
 
-      type = types.nullOr (types.list types.optionSet);
+      type = types.list types.optionSet;
 
       options = {