diff --git a/src/stores/WidgetEchoStore.ts b/src/stores/WidgetEchoStore.ts
index e752f3db20..09120d6108 100644
--- a/src/stores/WidgetEchoStore.ts
+++ b/src/stores/WidgetEchoStore.ts
@@ -16,6 +16,7 @@ limitations under the License.
 
 import EventEmitter from 'events';
 import { IWidget } from 'matrix-widget-api';
+import MatrixEvent from "matrix-js-sdk/src/models/event";
 import {WidgetType} from "../widgets/WidgetType";
 
 /**
@@ -36,7 +37,7 @@ class WidgetEchoStore extends EventEmitter {
             // Map as below. Object is the content of the widget state event,
             // so for widgets that have been deleted locally, the object is empty.
             // roomId: {
-            //     widgetId: [object]
+            //     widgetId: IWidget
             // }
         };
     }
@@ -48,11 +49,11 @@ class WidgetEchoStore extends EventEmitter {
      * and we don't really need the actual widget events anyway since we just want to
      * show a spinner / prevent widgets being added twice.
      *
-     * @param {Room} roomId The ID of the room to get widgets for
+     * @param {string} roomId The ID of the room to get widgets for
      * @param {MatrixEvent[]} currentRoomWidgets Current widgets for the room
      * @returns {MatrixEvent[]} List of widgets in the room, minus any pending removal
      */
-    getEchoedRoomWidgets(roomId, currentRoomWidgets) {
+    getEchoedRoomWidgets(roomId: string, currentRoomWidgets: MatrixEvent[]): MatrixEvent[] {
         const echoedWidgets = [];
 
         const roomEchoState = Object.assign({}, this.roomWidgetEcho[roomId]);
@@ -71,7 +72,7 @@ class WidgetEchoStore extends EventEmitter {
         return echoedWidgets;
     }
 
-    roomHasPendingWidgetsOfType(roomId, currentRoomWidgets, type?: WidgetType) {
+    roomHasPendingWidgetsOfType(roomId: string, currentRoomWidgets: MatrixEvent[], type?: WidgetType): boolean {
         const roomEchoState = Object.assign({}, this.roomWidgetEcho[roomId]);
 
         // any widget IDs that are already in the room are not pending, so
@@ -91,7 +92,7 @@ class WidgetEchoStore extends EventEmitter {
         }
     }
 
-    roomHasPendingWidgets(roomId, currentRoomWidgets) {
+    roomHasPendingWidgets(roomId: string, currentRoomWidgets: MatrixEvent[]): boolean {
         return this.roomHasPendingWidgetsOfType(roomId, currentRoomWidgets);
     }
 
@@ -102,7 +103,7 @@ class WidgetEchoStore extends EventEmitter {
         this.emit('update', roomId, widgetId);
     }
 
-    removeRoomWidgetEcho(roomId, widgetId) {
+    removeRoomWidgetEcho(roomId: string, widgetId: string) {
         delete this.roomWidgetEcho[roomId][widgetId];
         if (Object.keys(this.roomWidgetEcho[roomId]).length === 0) delete this.roomWidgetEcho[roomId];
         this.emit('update', roomId, widgetId);