diff --git a/demo/common/src/window.rs b/demo/common/src/window.rs
index 5d2fe0ec..6ca9852c 100644
--- a/demo/common/src/window.rs
+++ b/demo/common/src/window.rs
@@ -34,7 +34,9 @@ pub trait Window {
     fn present_open_svg_dialog(&mut self);
     fn run_save_dialog(&self, extension: &str) -> Result<PathBuf, ()>;
 
-    fn adjust_thread_pool_settings(&self, _: &mut ThreadPoolBuilder) {}
+    fn adjust_thread_pool_settings(&self, builder: ThreadPoolBuilder) -> ThreadPoolBuilder {
+        builder
+    }
 }
 
 pub enum Event {