diff --git a/activitystreams/activity.go b/activitystreams/activity.go
index e9097d0..0dec0c1 100644
--- a/activitystreams/activity.go
+++ b/activitystreams/activity.go
@@ -43,6 +43,7 @@ func NewCreateActivity(o *Object) *Activity {
 		BaseObject: BaseObject{
 			Context: []interface{}{
 				Namespace,
+				Extensions,
 			},
 			ID:   o.ID,
 			Type: "Create",
@@ -61,6 +62,7 @@ func NewUpdateActivity(o *Object) *Activity {
 		BaseObject: BaseObject{
 			Context: []interface{}{
 				Namespace,
+				Extensions,
 			},
 			ID:   o.ID,
 			Type: "Update",