diff --git a/desktop/package.json b/desktop/package.json
--- a/desktop/package.json
+++ b/desktop/package.json
@@ -36,6 +36,7 @@
     "electron": "^22.0.0",
     "flow-bin": "^0.182.0",
     "flow-typed": "^3.2.1",
+    "lib": "0.0.1",
     "fs-extra": "^10.1.0",
     "klaw": "^4.0.1"
   }
diff --git a/desktop/src/preload.js b/desktop/src/preload.js
--- a/desktop/src/preload.js
+++ b/desktop/src/preload.js
@@ -2,7 +2,9 @@
 
 import { contextBridge, ipcRenderer } from 'electron';
 
-const bridge = {
+import type { ElectronBridge } from 'lib/types/electron-types';
+
+const bridge: ElectronBridge = {
   onNavigate: callback => {
     const withEvent = (event, ...args) => callback(...args);
     ipcRenderer.on('on-navigate', withEvent);
diff --git a/lib/types/electron-types.js b/lib/types/electron-types.js
new file mode 100644
--- /dev/null
+++ b/lib/types/electron-types.js
@@ -0,0 +1,14 @@
+// @flow
+
+type OnNavigateListener = ({
+  +canGoBack: boolean,
+  +canGoForward: boolean,
+}) => void;
+
+export type ElectronBridge = {
+  // Returns a callback that you can call to remove the listener
+  +onNavigate: OnNavigateListener => () => void,
+  +clearHistory: () => void,
+  +doubleClickTopBar: () => void,
+  +setBadge: (number | string | null) => void,
+};
diff --git a/web/electron.js b/web/electron.js
--- a/web/electron.js
+++ b/web/electron.js
@@ -1,21 +1,10 @@
 // @flow
 
-type ElectronContextBridge = {
-  // Returns a callback that you can call to remove the listener
-  +onNavigate: OnNavigateListener => () => void,
-  +clearHistory: () => void,
-  +doubleClickTopBar: () => void,
-  +setBadge: (value: string | number | null) => void,
-};
+import type { ElectronBridge } from 'lib/types/electron-types';
 
-type OnNavigateListener = ({
-  +canGoBack: boolean,
-  +canGoForward: boolean,
-}) => void;
+declare var electronContextBridge: void | ElectronBridge;
 
-declare var electronContextBridge: ?ElectronContextBridge;
-
-const electron: null | ElectronContextBridge =
+const electron: ?ElectronBridge =
   typeof electronContextBridge === 'undefined' ? null : electronContextBridge;
 
 export default electron;