diff --git a/hosts/thrall/default.nix b/hosts/thrall/default.nix
index 8c045c8..6c860ab 100644
--- a/hosts/thrall/default.nix
+++ b/hosts/thrall/default.nix
@@ -2,7 +2,7 @@
 # your system.  Help is available in the configuration.nix(5) man page
 # and in the NixOS manual (accessible by running ‘nixos-help’).
 
-{ inputs, config, pkgs, ... }:
+{ inputs, lib, config, pkgs, ... }:
 let
   authorityFromUrl = url:
     builtins.head (pkgs.lib.drop 1 (pkgs.lib.splitString "://" url));
@@ -296,6 +296,10 @@ in {
       PAPERLESS_URL = "https://docs.failco.de";
       PAPERLESS_CONSUMER_RECURSIVE = true;
       PAPERLESS_CONSUMER_SUBDIRS_AS_TAGS = true;
+
+      # workaround for classification getting stuck, see
+      # https://github.com/NixOS/nixpkgs/issues/240591#issuecomment-1915678490
+      OMP_NUM_THREADS = 1;
     };
   };