diff --git a/PulseSensorAmpd_Processing_1dot1/serialEvent.pde b/PulseSensorAmpd_Processing_1dot1/serialEvent.pde
old mode 100755
new mode 100644
index 07e2910..83c11fc
--- a/PulseSensorAmpd_Processing_1dot1/serialEvent.pde
+++ b/PulseSensorAmpd_Processing_1dot1/serialEvent.pde
@@ -4,8 +4,13 @@
 
 void serialEvent(Serial port){ 
    String inData = port.readStringUntil('\n');
+   if (inData == null) {                 // bail if we didn't get anything
+     return;
+   }
    inData = trim(inData);                 // cut off white space (carriage return)
-   
+   if (inData.isEmpty()) {                // bail if we got an empty line
+     return;
+   }
    if (inData.charAt(0) == 'S'){          // leading 'S' for sensor data
      inData = inData.substring(1);        // cut off the leading 'S'
      Sensor = int(inData);                // convert the string to usable int
@@ -20,4 +25,4 @@ void serialEvent(Serial port){
      inData = inData.substring(1);        // cut off the leading 'Q'
      IBI = int(inData);                   // convert the string to usable int
    }
-}
+}