diff --git a/home-manager/progs/zen/default.nix b/home-manager/progs/zen/default.nix
index 797673a..ba616e0 100644
--- a/home-manager/progs/zen/default.nix
+++ b/home-manager/progs/zen/default.nix
@@ -109,6 +109,9 @@ in
         # https://github.com/nix-community/home-manager/issues/6083
         "services.sync.engine.prefs" = false;
         "services.sync.engine.addons" = false;
+        # use a separate default search engine in private windows
+        "browser.search.separatePrivateDefault.ui.enabled" = true;
+        "browser.search.separatePrivateDefault" = true;
         # disable built-in password manager — using bitwarden
         "signon.rememberSignons" = false;
         "signon.autofillForms" = false;