diff --git a/d2m/actions/remove-reaction.js b/d2m/actions/remove-reaction.js
new file mode 100644
index 0000000..821b9d0
--- /dev/null
+++ b/d2m/actions/remove-reaction.js
@@ -0,0 +1,36 @@
+// @ts-check
+
+const Ty = require("../../types")
+const assert = require("assert").strict
+
+const passthrough = require("../../passthrough")
+const {discord, sync, db, select} = passthrough
+/** @type {import("../../matrix/api")} */
+const api = sync.require("../../matrix/api")
+/** @type {import("./register-user")} */
+const registerUser = sync.require("./register-user")
+/** @type {import("../actions/create-room")} */
+const createRoom = sync.require("../actions/create-room")
+/** @type {import("../../matrix/file")} */
+const file = sync.require("../../matrix/file")
+
+/**
+ * @param {import("discord-api-types/v10").GatewayMessageReactionRemoveDispatchData} data
+ */
+async function removeReaction(data) {
+	const roomID = select("channel_room", "room_id", "WHERE channel_id = ?").pluck().get(data.channel_id)
+	if (!roomID) return
+	const eventIDForMessage = select("event_message", "event_id", "WHERE message_id = ? AND part = 0").pluck().get(data.message_id)
+	if (!eventIDForMessage) return
+	const mxid = select("sim", "mxid", "WHERE discord_id = ?").pluck().get(data.user_id)
+	if (!mxid) return
+
+	/** @type {Ty.Pagination<Ty.Event.Outer<Ty.Event.M_Reaction>>} */
+	const relations = await api.getRelations(roomID, eventIDForMessage, "m.annotation")
+	const eventIDForReaction = relations.chunk.find(e => e.sender === mxid && e.content["m.relates_to"].key === data.emoji) // TODO: get the key from the emoji
+	if (!eventIDForReaction) return
+
+	await api.redactEvent(roomID, eventIDForReaction, mxid)
+}
+
+module.exports.removeReaction = removeReaction
diff --git a/matrix/api.js b/matrix/api.js
index fa3aad3..c429216 100644
--- a/matrix/api.js
+++ b/matrix/api.js
@@ -1,7 +1,7 @@
 // @ts-check
 
 const Ty = require("../types")
-const assert = require("assert")
+const assert = require("assert").strict
 
 const passthrough = require("../passthrough")
 const { discord, sync, db } = passthrough
@@ -109,6 +109,18 @@ function getJoinedMembers(roomID) {
 	return mreq.mreq("GET", `/client/v3/rooms/${roomID}/joined_members`)
 }
 
+/**
+ * @param {string} roomID
+ * @param {string} eventID
+ * @param {string?} [relType]
+ * @returns {Promise<Ty.Pagination<Ty.Event.Outer<any>>>}
+ */
+function getRelations(roomID, eventID, relType) {
+	let path = `/client/v1/rooms/${roomID}/relations/${eventID}`
+	if (relType) path += `/${relType}`
+	return mreq.mreq("GET", path)
+}
+
 /**
  * @param {string} roomID
  * @param {string} type
@@ -207,6 +219,7 @@ module.exports.getEvent = getEvent
 module.exports.getAllState = getAllState
 module.exports.getStateEvent = getStateEvent
 module.exports.getJoinedMembers = getJoinedMembers
+module.exports.getRelations = getRelations
 module.exports.sendState = sendState
 module.exports.sendEvent = sendEvent
 module.exports.redactEvent = redactEvent
diff --git a/types.d.ts b/types.d.ts
index 3161b14..db72eb3 100644
--- a/types.d.ts
+++ b/types.d.ts
@@ -215,3 +215,9 @@ export namespace R {
 		event_id: string
 	}
 }
+
+export type Pagination<T> {
+	chunk: T[]
+	next_batch?: string
+	prev_match?: string
+}