diff --git a/react/features/app/types.ts b/react/features/app/types.ts
index 896371e59..41ffe3bcb 100644
--- a/react/features/app/types.ts
+++ b/react/features/app/types.ts
@@ -6,6 +6,8 @@ import { IAudioOnlyState } from '../base/audio-only/reducer';
 import { IConferenceState } from '../base/conference/reducer';
 import { IConfig } from '../base/config/configType';
 import { IConnectionState } from '../base/connection/reducer';
+import { IDevicesState } from '../base/devices/reducer';
+import { IDialogState } from '../base/dialog/reducer';
 
 export interface IStore {
     getState: Function,
@@ -20,5 +22,7 @@ export interface IState {
     'features/base/audio-only': IAudioOnlyState,
     'features/base/conference': IConferenceState,
     'features/base/config': IConfig,
-    'features/base/connection': IConnectionState
+    'features/base/connection': IConnectionState,
+    'features/base/devices': IDevicesState,
+    'features/base/dialog': IDialogState
 }
diff --git a/react/features/base/devices/reducer.js b/react/features/base/devices/reducer.ts
similarity index 78%
rename from react/features/base/devices/reducer.js
rename to react/features/base/devices/reducer.ts
index 457be5931..ab5bd5c0f 100644
--- a/react/features/base/devices/reducer.js
+++ b/react/features/base/devices/reducer.ts
@@ -1,4 +1,5 @@
-import { ReducerRegistry } from '../redux';
+/* eslint-disable import/order */
+import ReducerRegistry from '../redux/ReducerRegistry';
 
 import {
     ADD_PENDING_DEVICE_REQUEST,
@@ -8,10 +9,15 @@ import {
     SET_VIDEO_INPUT_DEVICE,
     UPDATE_DEVICE_LIST
 } from './actionTypes';
+
+// @ts-ignore
 import { groupDevicesByKind } from './functions';
+
+// @ts-ignore
 import logger from './logger';
 
-const DEFAULT_STATE = {
+
+const DEFAULT_STATE: IDevicesState = {
     availableDevices: {
         audioInput: [],
         audioOutput: [],
@@ -24,10 +30,23 @@ const DEFAULT_STATE = {
     }
 };
 
+export interface IDevicesState {
+    availableDevices: {
+        audioInput: MediaDeviceInfo[];
+        audioOutput: MediaDeviceInfo[];
+        videoInput: MediaDeviceInfo[];
+    };
+    pendingRequests: Object[];
+    permissions: {
+        audio: boolean;
+        video: boolean;
+    }
+}
+
 /**
  * Listen for actions which changes the state of known and used devices.
  *
- * @param {Object} state - The Redux state of the feature features/base/devices.
+ * @param {IDevicesState} state - The Redux state of the feature features/base/devices.
  * @param {Object} action - Action object.
  * @param {string} action.type - Type of action.
  * @param {Array<MediaDeviceInfo>} action.devices - All available audio and
@@ -36,7 +55,7 @@ const DEFAULT_STATE = {
  */
 ReducerRegistry.register(
     'features/base/devices',
-    (state = DEFAULT_STATE, action) => {
+    (state: IDevicesState = DEFAULT_STATE, action) => {
         switch (action.type) {
         case UPDATE_DEVICE_LIST: {
             const deviceList = groupDevicesByKind(action.devices);
diff --git a/react/features/base/dialog/reducer.js b/react/features/base/dialog/reducer.ts
similarity index 75%
rename from react/features/base/dialog/reducer.js
rename to react/features/base/dialog/reducer.ts
index 56b47911b..75897d5e0 100644
--- a/react/features/base/dialog/reducer.js
+++ b/react/features/base/dialog/reducer.ts
@@ -1,4 +1,5 @@
-import { assign, ReducerRegistry } from '../redux';
+import ReducerRegistry from '../redux/ReducerRegistry';
+import { assign } from '../redux/functions';
 
 import {
     HIDE_DIALOG,
@@ -7,16 +8,23 @@ import {
     OPEN_SHEET
 } from './actionTypes';
 
+export interface IDialogState {
+    component?: Object;
+    componentProps?: Object;
+    sheet?: Object;
+    sheetProps?: Object;
+}
+
 /**
  * Reduces redux actions which show or hide dialogs.
  *
- * @param {State} state - The current redux state.
+ * @param {IDialogState} state - The current redux state.
  * @param {Action} action - The redux action to reduce.
  * @param {string} action.type - The type of the redux action to reduce..
  * @returns {State} The next redux state that is the result of reducing the
  * specified action.
  */
-ReducerRegistry.register('features/base/dialog', (state = {}, action) => {
+ReducerRegistry.register('features/base/dialog', (state: IDialogState = {}, action) => {
     switch (action.type) {
     case HIDE_DIALOG: {
         const { component } = action;