diff --git a/lib/pcsclite.js b/lib/pcsclite.js
index d3f0cbe..09cc4ad 100644
--- a/lib/pcsclite.js
+++ b/lib/pcsclite.js
@@ -88,7 +88,10 @@ CardReader.prototype.connect = function(options, cb) {
 
     options = options || {};
     options.share_mode = options.share_mode || this.SCARD_SHARE_EXCLUSIVE;
-    options.protocol = options.protocol || this.SCARD_PROTOCOL_T0 | this.SCARD_PROTOCOL_T1;
+
+    if (typeof options.protocol === 'undefined' || options.protocol === null) {
+        options.protocol = this.SCARD_PROTOCOL_T0 | this.SCARD_PROTOCOL_T1;
+    }
 
     if (!this.connected) {
         this._connect(options.share_mode, options.protocol, cb);