diff --git a/lib/modem/index.js b/lib/modem/index.js
index 2b92616..b6f8661 100644
--- a/lib/modem/index.js
+++ b/lib/modem/index.js
@@ -38,7 +38,7 @@ class Modem extends EventEmitter {
         const self = this;
 
         debugLog('MODEM: opening ' + this.portName);
-        this.port = new SerialPort(this.portName, portOptions);
+        this.port = new SerialPort(this.portName, this.portOptions);
 
         this.port.on('error', function(err) {
             debugLog('MODEM: error opening ' + this.portName);