diff --git a/lib/useragent-base.js b/lib/useragent-base.js
index b596fb9..64d543e 100755
--- a/lib/useragent-base.js
+++ b/lib/useragent-base.js
@@ -2558,6 +2558,12 @@ module.exports = (function () {
 
         detect: function (ua) {
 
+            // when ua is not a string, just do not detect it slient
+            if(typeof ua !== 'string') {
+                // throw new TypeError('ua must be a string')
+                return this;
+            }
+
             /****************************************************
              *      Unix
              */