diff --git a/doc/Jamfile.v2 b/doc/Jamfile.v2
index 41c0dcc..48e587f 100644
--- a/doc/Jamfile.v2
+++ b/doc/Jamfile.v2
@@ -10,6 +10,7 @@ boostbook tribool
 	: 
 	tribool.boostbook 
 	:
+	    <xsl:param>boost.root=../../../..
         <format>pdf:<xsl:param>boost.url.prefix=http://www.boost.org/doc/libs/release/doc/html
         <dependency>reference
 	;