diff --git a/doc/Jamfile.v2 b/doc/Jamfile.v2
index 41c0dcc..422ea5e 100644
--- a/doc/Jamfile.v2
+++ b/doc/Jamfile.v2
@@ -7,9 +7,10 @@ doxygen reference : [ glob ../../../boost/logic/tribool.hpp ]
                     [ glob ../../../boost/logic/tribool_io.hpp ]
                   ;
 boostbook tribool 
-	: 
-	tribool.boostbook 
-	:
+    : 
+    tribool.boostbook 
+    :
+        <xsl:param>boost.root=../../../..
         <format>pdf:<xsl:param>boost.url.prefix=http://www.boost.org/doc/libs/release/doc/html
         <dependency>reference
-	;
+    ;