diff --git a/lib/browser/api/protocol.js b/lib/browser/api/protocol.js
index d1c26991d0e3..9d8394f76754 100644
--- a/lib/browser/api/protocol.js
+++ b/lib/browser/api/protocol.js
@@ -1,4 +1,4 @@
-const {session} = require('electron')
+const {app, session} = require('electron')
 
 // Global protocol APIs.
 module.exports = process.atomBinding('protocol')
@@ -6,10 +6,18 @@ module.exports = process.atomBinding('protocol')
 // Fallback protocol APIs of default session.
 Object.setPrototypeOf(module.exports, new Proxy({}, {
   get (target, property) {
-    return (...args) => session.defaultSession.protocol[property](...args)
+    if (!app.isReady()) return
+
+    const protocol = session.defaultSession.protocol
+    if (!protocol.hasOwnProperty(property)) return
+
+    // Returning a native function directly would throw error.
+    return (...args) => protocol[property](...args)
   },
 
   ownKeys () {
+    if (!app.isReady()) return []
+
     return Object.getOwnPropertyNames(session.defaultSession.protocol)
   },