diff --git a/api/client-server/v1/sync.yaml b/api/client-server/v1/sync.yaml
index 833c425a..8fe30056 100644
--- a/api/client-server/v1/sync.yaml
+++ b/api/client-server/v1/sync.yaml
@@ -267,6 +267,12 @@ paths:
                       type: string
                       description: "The user's membership state in this room."
                       enum: ["invite", "join", "leave", "ban"]
+                    invite:
+                        type: object
+                        title: "InviteEvent"
+                        description: "The invite event if ``membership`` is ``invite``"
+                        allOf:
+                          - "$ref": "v1-event-schema/m.room.member"
                     messages:
                       type: object
                       title: PaginationChunk
diff --git a/event-schemas/schema/v1/m.room.member b/event-schemas/schema/v1/m.room.member
index 49b9f5b8..c0fb103c 100644
--- a/event-schemas/schema/v1/m.room.member
+++ b/event-schemas/schema/v1/m.room.member
@@ -32,6 +32,26 @@
         "type": {
             "type": "string",
             "enum": ["m.room.member"]
+        },
+        "invite_room_state": {
+            "type": "array",
+            "description": "A subset of the state of the room at the time of the invite, if ``membership`` is ``invite``",
+            "items": {
+                "type": "object",
+                "title": "StateEvent",
+                "description": "A stripped down state event, with only the ``type``, ``state_key`` and ``content`` keys.",
+                "properties": {
+                    "type": {
+                        "type": "string"
+                    },
+                    "state_key": {
+                        "type": "string"
+                    },
+                    "content": {
+                        "type": "object"
+                    }
+                }
+            }
         }
     }
 }