diff --git a/src/boxerror.js b/src/boxerror.js
index 1767689ec..ff78e7dd7 100644
--- a/src/boxerror.js
+++ b/src/boxerror.js
@@ -8,10 +8,10 @@ const assert = require('assert'),
 
 exports = module.exports = BoxError;
 
-function BoxError(reason, errorOrMessage, extra) {
+function BoxError(reason, errorOrMessage, extra = {}) {
     assert.strictEqual(typeof reason, 'string');
     assert(errorOrMessage instanceof Error || typeof errorOrMessage === 'string');
-    assert(typeof extra === 'object' || typeof extra === 'undefined');
+    assert(typeof extra === 'object');
 
     Error.call(this);
     Error.captureStackTrace(this, this.constructor);
@@ -20,20 +20,18 @@ function BoxError(reason, errorOrMessage, extra) {
     this.reason = reason;
     this.details = {};
 
-    if (typeof errorOrMessage === 'undefined') {
-        this.message = reason;
-    } else if (typeof errorOrMessage === 'string') {
+    if (typeof errorOrMessage === 'string') {
         this.message = errorOrMessage;
     } else if (errorOrMessage instanceof AggregateError) { //
         const messages = errorOrMessage.errors.map(e => e.message);
         this.message = `${errorOrMessage.message} messages: ${messages.join(',')}`;
         this.nestedError = errorOrMessage;
-        Object.assign(this, extra);
     } else { // error object
         this.message = errorOrMessage.message;
         this.nestedError = errorOrMessage;
-        Object.assign(this, extra);
     }
+
+    Object.assign(this, extra);
 }
 util.inherits(BoxError, Error);
 BoxError.ACCESS_DENIED = 'Access Denied';