diff --git a/container.go b/container.go
index 00e9512..9b3f12d 100644
--- a/container.go
+++ b/container.go
@@ -4,6 +4,8 @@ import "image"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/event"
 
+var _ tomo.ContentObject = new(Container)
+
 // Container is an object that can contain other objects. It can be used as a
 // primitive for building more complex layouts. It has two variants: an outer
 // container, and an inner container. The outer container has padding around