diff --git a/examples/Example4-ProcessingHeatCam/HeatCam/HeatCam.pde b/examples/Example4-ProcessingHeatCam/HeatCam/HeatCam.pde
index 76b8287..6fba64d 100644
--- a/examples/Example4-ProcessingHeatCam/HeatCam/HeatCam.pde
+++ b/examples/Example4-ProcessingHeatCam/HeatCam/HeatCam.pde
@@ -72,6 +72,11 @@ void draw() {
   if(myPort.available() > 64){
   myString = myPort.readStringUntil(13);
   
+  // readStringUntil is a non-blocking function and will return null if it can't find the linefeed
+  if(myString == null){
+    return;
+  }
+  
   // generate an array of strings that contains each of the comma
   // separated values
   String splitString[] = splitTokens(myString, ",");
@@ -117,4 +122,4 @@ void draw() {
   // Add a gaussian blur to the canvas in order to create a rough
   // visual interpolation between pixels.
   filter(BLUR,10);
-} 
\ No newline at end of file
+}