diff --git a/activitystreams/activity.go b/activitystreams/activity.go
index aae78f0..46b3b48 100644
--- a/activitystreams/activity.go
+++ b/activitystreams/activity.go
@@ -1,55 +1,58 @@
 package activitystreams
 
 import (
 	"time"
 )
 
 const (
 	toPublic = "https://www.w3.org/ns/activitystreams#Public"
 )
 
 type Activity struct {
 	BaseObject
 	Actor     string    `json:"actor"`
 	Published time.Time `json:"published,omitempty"`
 	To        []string  `json:"to,omitempty"`
 	CC        []string  `json:"cc,omitempty"`
 	Object    *Object   `json:"object"`
 }
 
 func NewCreateActivity(o *Object) *Activity {
 	a := Activity{
 		BaseObject: BaseObject{
+			Context: []string{
+				"https://www.w3.org/ns/activitystreams",
+			},
 			ID:   o.ID + "/activity",
 			Type: "Create",
 		},
 		Actor:  o.AttributedTo,
 		Object: o,
 	}
 	return &a
 }
 
 type Object struct {
 	BaseObject
 	Published    time.Time         `json:"published"`
 	Summary      *string           `json:"summary,omitempty"`
 	InReplyTo    *string           `json:"inReplyTo"`
 	URL          string            `json:"url"`
 	AttributedTo string            `json:"attributedTo"`
 	To           []string          `json:"to"`
 	CC           []string          `json:"cc,omitempty"`
 	Content      string            `json:"content"`
 	ContentMap   map[string]string `json:"contentMap,omitempty"`
 }
 
 func NewNoteObject() *Object {
 	o := Object{
 		BaseObject: BaseObject{
 			Type: "Note",
 		},
 		To: []string{
 			toPublic,
 		},
 	}
 	return &o
 }