diff --git a/src/apps/rednatco/controls.tsx b/src/apps/rednatco/controls.tsx
index f72e9e58c3617b990b3b6710e528cb233b226a86..11ee3a5b36b3c31cc7a9caf2db2d73d154a639e5 100644
--- a/src/apps/rednatco/controls.tsx
+++ b/src/apps/rednatco/controls.tsx
@@ -26,6 +26,7 @@ export class CollapsibleVertical extends React.Component<CollapsibleVertical.Pro
 export namespace CollapsibleVertical {
     export interface Props {
         caption: string;
+        children?: React.ReactNode;
     }
 }