diff --git a/INSTALL b/INSTALL
index ad6c4cc5..437f8144 100644
--- a/INSTALL
+++ b/INSTALL
@@ -18,6 +18,7 @@ Generating documentation:
 
 - asciidoc - text document format tool
 - xmlto - text document format tool
+- source-highlight - optional, only for generating HTML output
 
 XATTR library should be provided by the standard C library or by