diff --git a/egui_demo_lib/src/apps/custom_3d.rs b/egui_demo_lib/src/apps/custom_3d.rs
index e24bb5c2..01a8a870 100644
--- a/egui_demo_lib/src/apps/custom_3d.rs
+++ b/egui_demo_lib/src/apps/custom_3d.rs
@@ -47,6 +47,10 @@ impl epi::App for Custom3dApp {
             });
         });
     }
+
+    fn on_exit(&mut self, gl: &glow::Context) {
+        self.rotating_triangle.lock().destroy(gl);
+    }
 }
 
 impl Custom3dApp {
@@ -166,8 +170,6 @@ impl RotatingTriangle {
         }
     }
 
-    // TODO: figure out how to call this in a nice way
-    #[allow(unused)]
     fn destroy(self, gl: &glow::Context) {
         use glow::HasContext as _;
         unsafe {
diff --git a/egui_demo_lib/src/wrap_app.rs b/egui_demo_lib/src/wrap_app.rs
index 324e183a..e23d212e 100644
--- a/egui_demo_lib/src/wrap_app.rs
+++ b/egui_demo_lib/src/wrap_app.rs
@@ -132,6 +132,15 @@ impl epi::App for WrapApp {
 
         self.ui_file_drag_and_drop(ctx);
     }
+
+    fn on_exit(&mut self, gl: &glow::Context) {
+        self.apps.demo.on_exit(gl);
+        self.apps.easy_mark_editor.on_exit(gl);
+        self.apps.http.on_exit(gl);
+        self.apps.clock.on_exit(gl);
+        self.apps.color_test.on_exit(gl);
+        self.apps.custom_3d.on_exit(gl);
+    }
 }
 
 impl WrapApp {