diff --git a/How-to-build.md b/How-to-build.md
index 8d28778..b7d6215 100644
--- a/How-to-build.md
+++ b/How-to-build.md
@@ -75,7 +75,7 @@ At the front is a spot to solder a 3mm status LED together with its resistor(1K
 
 ![image](https://dl.dropboxusercontent.com/s/k1rr7w69n6d08j1/hw5rev1led.jpg?dl=1)  
 
-On the back you need to close the solder jumper marked in red.    
+If you have an older version of the main PCB (prior to Rev.5) you also need to close the solder jumper marked in red on the back of the main PCB.    
 
 ![image](https://dl.dropboxusercontent.com/s/lfx3ggobp5mzifb/wrhgaeghagehageage.jpg?dl=1)