diff --git a/masonry/src/widget/zstack.rs b/masonry/src/widget/zstack.rs
index 658217d26..3ffd2d820 100644
--- a/masonry/src/widget/zstack.rs
+++ b/masonry/src/widget/zstack.rs
@@ -10,6 +10,7 @@ struct Child {
     widget: WidgetPod<Box<dyn Widget>>,
 }
 
+#[derive(Default)]
 pub struct ZStack {
     children: Vec<Child>,
 }
diff --git a/xilem/src/view/zstack.rs b/xilem/src/view/zstack.rs
index fdaebce9f..6b3407941 100644
--- a/xilem/src/view/zstack.rs
+++ b/xilem/src/view/zstack.rs
@@ -88,7 +88,7 @@ impl ViewElement for ZStackElement {
 }
 
 impl SuperElement<ZStackElement, ViewCtx> for ZStackElement {
-    fn upcast(ctx: &mut ViewCtx, child: ZStackElement) -> Self {
+    fn upcast(_ctx: &mut ViewCtx, child: ZStackElement) -> Self {
         child
     }