diff --git a/lib/mix/tasks/pleroma/database.ex b/lib/mix/tasks/pleroma/database.ex
index 726a22d41..55d1c8ddc 100644
--- a/lib/mix/tasks/pleroma/database.ex
+++ b/lib/mix/tasks/pleroma/database.ex
@@ -171,6 +171,21 @@ defmodule Mix.Tasks.Pleroma.Database do
     end
     |> Repo.delete_all(timeout: :infinity)
 
+    if !Keyword.get(options, :keep_threads) do
+      # Without the --keep-threads option, it's possible that bookmarked
+      # objects have been deleted. We remove the corresponding bookmarks.
+      """
+      delete from public.bookmarks
+      where id in (
+        select b.id from public.bookmarks b
+        left join public.activities a on b.activity_id = a.id
+        left join public.objects o on a."data" ->> 'object' = o.data ->> 'id'
+        where o.id is null
+      )
+      """
+      |> Repo.query([], timeout: :infinity)
+    end
+
     if Keyword.get(options, :prune_orphaned_activities) do
       # Prune activities who link to a single object
       """
diff --git a/test/mix/tasks/pleroma/database_test.exs b/test/mix/tasks/pleroma/database_test.exs
index 21c365412..40c5fd402 100644
--- a/test/mix/tasks/pleroma/database_test.exs
+++ b/test/mix/tasks/pleroma/database_test.exs
@@ -7,6 +7,7 @@ defmodule Mix.Tasks.Pleroma.DatabaseTest do
   use Oban.Testing, repo: Pleroma.Repo
 
   alias Pleroma.Activity
+  alias Pleroma.Bookmark
   alias Pleroma.Object
   alias Pleroma.Repo
   alias Pleroma.User
@@ -87,6 +88,29 @@ defmodule Mix.Tasks.Pleroma.DatabaseTest do
       refute Object.get_by_id(note_remote_non_public_id)
     end
 
+    test "it cleans up bookmarks", %{old_insert_date: old_insert_date} do
+      user = insert(:user)
+      {:ok, old_object_activity} = CommonAPI.post(user, %{status: "yadayada"})
+
+      Repo.one(Object)
+      |> Ecto.Changeset.change(%{updated_at: old_insert_date})
+      |> Repo.update!()
+
+      {:ok, new_object_activity} = CommonAPI.post(user, %{status: "yadayada"})
+
+      {:ok, _} = Bookmark.create(user.id, old_object_activity.id)
+      {:ok, _} = Bookmark.create(user.id, new_object_activity.id)
+
+      assert length(Repo.all(Object)) == 2
+      assert length(Repo.all(Bookmark)) == 2
+
+      Mix.Tasks.Pleroma.Database.run(["prune_objects"])
+
+      assert length(Repo.all(Object)) == 1
+      assert length(Repo.all(Bookmark)) == 1
+      refute Bookmark.get(user.id, old_object_activity.id)
+    end
+
     test "with the --keep-non-public option it still keeps non-public posts even if they are not local",
          %{old_insert_date: old_insert_date} do
       insert(:note)