diff --git a/demo/android/rust/src/lib.rs b/demo/android/rust/src/lib.rs
index 78f27037..b3ddfb02 100644
--- a/demo/android/rust/src/lib.rs
+++ b/demo/android/rust/src/lib.rs
@@ -167,7 +167,7 @@ impl Window for WindowImpl {
         Point2DI32::new(0, 0)
     }
 
-    fn present(&self) {}
+    fn present(&mut self) {}
 
     fn resource_loader(&self) -> &dyn ResourceLoader {
         &RESOURCE_LOADER
diff --git a/demo/common/src/window.rs b/demo/common/src/window.rs
index 1fbd08e0..d6e00795 100644
--- a/demo/common/src/window.rs
+++ b/demo/common/src/window.rs
@@ -22,7 +22,7 @@ pub trait Window {
     fn gl_version(&self) -> GLVersion;
     fn gl_default_framebuffer(&self) -> GLuint { 0 }
     fn mouse_position(&self) -> Point2DI32;
-    fn present(&self);
+    fn present(&mut self);
     fn resource_loader(&self) -> &dyn ResourceLoader;
     fn create_user_event_id(&self) -> u32;
     fn push_user_event(message_type: u32, message_data: u32);
diff --git a/demo/native/src/main.rs b/demo/native/src/main.rs
index ef5cec8e..a1264142 100644
--- a/demo/native/src/main.rs
+++ b/demo/native/src/main.rs
@@ -78,7 +78,7 @@ impl Window for WindowImpl {
         Point2DI32::new(mouse_state.x(), mouse_state.y())
     }
 
-    fn present(&self) {
+    fn present(&mut self) {
         self.window.gl_swap_window();
     }