diff --git a/README.md b/README.md
index 3f18b1d..e2e2753 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 Master XSLT stylesheets for the INFO database authoring framework.
 
+You will need SAXON-B installed in order to process these successfully. The final released version of SAXON-B is 9.1.0.8. Earlier versions may not support the required features, and later versions change the architecture in ways that will probably break this framework!
+
 To install:
 
 	% git clone https://github.com/Otago-InfoSci-Database/XML.git