diff --git a/doc/Jamfile.v2 b/doc/Jamfile.v2
index a52f697..d73d31d 100644
--- a/doc/Jamfile.v2
+++ b/doc/Jamfile.v2
@@ -49,7 +49,7 @@ boostbook standalone
     <xsl:param>boost.root=../../../..
     <xsl:param>generate.section.toc.level=1
     <xsl:param>toc.max.depth=1
-    <format>pdf:<xsl:param>boost.url.prefix=http://www.boost.org/doc/libs/release/libs/core/doc/html
+    <format>pdf:<xsl:param>boost.url.prefix="http://www.boost.org/doc/libs/release/libs/core/doc/html"
   ;
 
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