diff --git a/README.md b/README.md
index 60feaf2..62cdc33 100644
--- a/README.md
+++ b/README.md
@@ -6,4 +6,4 @@ Arduino support libraries and demo code for Didels Witty 2WD balancing robot.
 ## Documents
 [Witty Quick Start Guide](extras/WittyQuickStartGuide.pdf)  
 [Witty Specs (PDF)](extras/WittySpecs.pdf)  
- 
+[Witty Specs (PDF)](extras/WittySoft.pdf)