diff --git a/doc/Build.txt b/doc/Build.txt
index cde1429c162e843981b74041f8077e4fa9e48a63..763505c4aa4d03db586288ea675e5ec49a70567f 100644
--- a/doc/Build.txt
+++ b/doc/Build.txt
@@ -30,6 +30,7 @@ libiax2
 Go to `libs/libiax2` and run:
 
 -------------------------
+./gen.sh
 ./configure --prefix=/usr
 make
 sudo make install