diff --git a/spec/unit/ReEmitter.spec.ts b/spec/unit/ReEmitter.spec.ts
new file mode 100644
index 000000000..d1c853fe6
--- /dev/null
+++ b/spec/unit/ReEmitter.spec.ts
@@ -0,0 +1,49 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { EventEmitter } from "events";
+import { ReEmitter } from "../../src/ReEmitter";
+
+const EVENTNAME = "UnknownEntry";
+
+class EventSource extends EventEmitter {
+    doTheThing() {
+        this.emit(EVENTNAME, "foo", "bar");
+    }
+}
+
+class EventTarget extends EventEmitter {
+
+}
+
+describe("ReEmitter", function() {
+    it("Re-Emits events with the same args", function() {
+        const src = new EventSource();
+        const tgt = new EventTarget();
+
+        const handler = jest.fn();
+        tgt.on(EVENTNAME, handler);
+
+        const reEmitter = new ReEmitter(tgt);
+        reEmitter.reEmit(src, [EVENTNAME]);
+
+        src.doTheThing();
+
+        // Args should be the args passed to 'emit' after the event name, and
+        // also the source object of the event which re-emitter adds
+        expect(handler).toHaveBeenCalledWith("foo", "bar", src);
+    });
+});
diff --git a/src/ReEmitter.js b/src/ReEmitter.js
deleted file mode 100644
index 84a856bb2..000000000
--- a/src/ReEmitter.js
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
-Copyright 2015, 2016 OpenMarket Ltd
-Copyright 2017 Vector Creations Ltd
-Copyright 2017 New Vector Ltd
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-/**
- * @module
- */
-
-export class ReEmitter {
-    constructor(target) {
-        this.target = target;
-
-        // We keep one bound event handler for each event name so we know
-        // what event is arriving
-        this.boundHandlers = {};
-    }
-
-    _handleEvent(eventName, ...args) {
-        this.target.emit(eventName, ...args);
-    }
-
-    reEmit(source, eventNames) {
-        // We include the source as the last argument for event handlers which may need it,
-        // such as read receipt listeners on the client class which won't have the context
-        // of the room.
-        const forSource = (handler, ...args) => {
-            handler(...args, source);
-        };
-        for (const eventName of eventNames) {
-            if (this.boundHandlers[eventName] === undefined) {
-                this.boundHandlers[eventName] = this._handleEvent.bind(this, eventName);
-            }
-
-            const boundHandler = forSource.bind(this, this.boundHandlers[eventName]);
-            source.on(eventName, boundHandler);
-        }
-    }
-}
diff --git a/src/ReEmitter.ts b/src/ReEmitter.ts
new file mode 100644
index 000000000..f65912aa4
--- /dev/null
+++ b/src/ReEmitter.ts
@@ -0,0 +1,39 @@
+/*
+Copyright 2015, 2016 OpenMarket Ltd
+Copyright 2017 Vector Creations Ltd
+Copyright 2017 New Vector Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { EventEmitter } from "events";
+
+export class ReEmitter {
+    private target: EventEmitter;
+
+    constructor(target: EventEmitter) {
+        this.target = target;
+    }
+
+    reEmit(source: EventEmitter, eventNames: string[]) {
+        for (const eventName of eventNames) {
+            // We include the source as the last argument for event handlers which may need it,
+            // such as read receipt listeners on the client class which won't have the context
+            // of the room.
+            const forSource = (...args) => {
+                this.target.emit(eventName, ...args, source);
+            };
+            source.on(eventName, forSource);
+        }
+    }
+}