diff --git a/src/tools/boostbook.jam b/src/tools/boostbook.jam
index b7f1965d9..71d6bdd2b 100644
--- a/src/tools/boostbook.jam
+++ b/src/tools/boostbook.jam
@@ -108,7 +108,53 @@ rule init (
     
     # The same about Jamfile main target rules.
     IMPORT $(__name__) : boostbook : : boostbook ;
-  }    
+  }
+  else
+  {
+    if $(docbook-xsl-dir) 
+    {
+      modify-config ;
+      .docbook-xsl-dir = [ path.make $(docbook-xsl-dir) ] ;
+      check-docbook-xsl-dir ;
+    }
+    if $(docbook-dtd-dir) 
+    {
+      modify-config ;
+      .docbook-dtd-dir = [ path.make $(docbook-dtd-dir) ] ;
+      check-docbook-dtd-dir ;
+    }
+    if $(boostbook-dir)
+    {
+      modify-config ;
+      check-boostbook-dir $(boostbook-dir) ;
+      local boostbook-xsl-dir = [ path.glob $(boostbook-dir) : xsl ] ;
+      local boostbook-dtd-dir = [ path.glob $(boostbook-dir) : dtd ] ;
+      .boostbook-xsl-dir = $(boostbook-xsl-dir[1]) ;
+      .boostbook-dtd-dir = $(boostbook-dtd-dir[1]) ;
+      check-boostbook-xsl-dir ;
+      check-boostbook-dtd-dir ;
+    }
+  }
+}
+
+rule lock-config ( )
+{
+  if ! $(.initialized)
+  {
+    errors.user-error "BoostBook has not been configured." ;
+  }
+  if ! $(.config-locked)
+  {
+    .config-locked = true ;
+  }
+}
+
+rule modify-config ( )
+{
+  if $(.config-locked)
+  {
+    errors.user-error "BoostBook configuration cannot be changed after it has been used." ;
+  }
 }
 
 rule find-boost-in-registry ( keys * )
@@ -127,6 +173,88 @@ rule find-boost-in-registry ( keys * )
   return $(boost-root) ;
 }
 
+rule check-docbook-xsl-dir ( )
+{
+  if $(.docbook-xsl-dir)
+  {
+    if ! [ path.glob $(.docbook-xsl-dir) : common/common.xsl ]
+    {
+      errors.user-error "BoostBook: could not find docbook XSL stylesheets in:" [ path.native $(.docbook-xsl-dir) ] ;
+    }
+    else
+    {
+      if --debug-configuration in [ modules.peek : ARGV ]
+      {
+        ECHO "notice: BoostBook: found docbook XSL stylesheets in:" [ path.native $(.docbook-xsl-dir) ] ;
+      }
+    }
+  }
+}
+
+rule check-docbook-dtd-dir ( )
+{
+  if $(.docbook-dtd-dir)
+  {
+    if ! [ path.glob $(.docbook-dtd-dir) : docbookx.dtd ]
+    {
+      errors.user-error "error: BoostBook: could not find docbook DTD in:" [ path.native $(.docbook-dtd-dir) ] ;
+    }
+    else
+    {
+      if --debug-configuration in [ modules.peek : ARGV ]
+      {
+        ECHO "notice: BoostBook: found docbook DTD in:" [ path.native $(.docbook-dtd-dir) ] ;
+      }
+    }
+  }
+}
+
+rule check-boostbook-xsl-dir ( )
+{
+  if ! $(.boostbook-xsl-dir)
+  {
+    errors.user-error "error: BoostBook: could not find boostbook XSL stylesheets." ;
+  }
+  else if ! [ path.glob $(.boostbook-xsl-dir) : docbook.xsl ]
+  {
+    errors.user-error "error: BoostBook: could not find docbook XSL stylesheets in:" [ path.native $(.boostbook-xsl-dir) ] ;
+  }
+  else
+  {
+    if --debug-configuration in [ modules.peek : ARGV ]
+    {
+      ECHO "notice: BoostBook: found boostbook XSL stylesheets in:" [ path.native $(.boostbook-xsl-dir) ] ;
+    }
+  }
+}
+
+rule check-boostbook-dtd-dir ( )
+{
+  if ! $(.boostbook-dtd-dir)
+  {
+    errors.user-error "error: BoostBook: could not find boostbook DTD." ;
+  }
+  else if ! [ path.glob $(.boostbook-dtd-dir) : boostbook.dtd ]
+  {
+    errors.user-error "error: BoostBook: could not find boostbook DTD in:" [ path.native $(.boostbook-dtd-dir) ] ;
+  }
+  else
+  {
+    if --debug-configuration in [ modules.peek : ARGV ]
+    {
+      ECHO "notice: BoostBook: found boostbook DTD in:" [ path.native $(.boostbook-dtd-dir) ] ;
+    }
+  }
+}
+
+rule check-boostbook-dir ( boostbook-dir ? )
+{
+  if $(boostbook-dir) && ! [ path.glob $(boostbook-dir) : xsl ]
+  {
+    errors.user-error "error: BoostBook: could not find boostbook in:" [ path.native $(boostbook-dir) ] ;
+  }
+}
+
 rule find-tools ( docbook-xsl-dir ? : docbook-dtd-dir ? : boostbook-dir ? )
 {
   docbook-xsl-dir ?= [ modules.peek : DOCBOOK_XSL_DIR ] ;
@@ -234,101 +362,89 @@ rule find-tools ( docbook-xsl-dir ? : docbook-dtd-dir ? : boostbook-dir ? )
   .boostbook-xsl-dir = $(boostbook-xsl-dir[1]) ;
   .boostbook-dtd-dir = $(boostbook-dtd-dir[1]) ;
 
-  if --debug-configuration in [ modules.peek : ARGV ]
-  {
-    if $(.docbook-xsl-dir)
-    {
-      ECHO "notice: Boost.Book: found docbook XSL stylesheets in:" [ path.native $(.docbook-xsl-dir) ] ;
-    }
-    if $(.docbook-dtd-dir)
-    {
-      ECHO "notice: Boost.Book: found docbook DTD in:" [ path.native $(.docbook-dtd-dir) ] ;
-    }
-    if $(.boostbook-xsl-dir)
-    {
-      ECHO "notice: Boost.Book: found boostbook XSL stylesheets in:" [ path.native $(.boostbook-xsl-dir) ] ;
-    }
-    if $(.boostbook-dtd-dir)
-    {
-      ECHO "notice: Boost.Book: found boostbook DTD in:" [ path.native $(.boostbook-dtd-dir) ] ;
-    }
-  }
-
-  if ! $(.boostbook-xsl-dir) || ! $(.boostbook-dtd-dir)
-  {
-    errors.warning
-      "couldn't find BoostBook xsl or dtd directories;" 
-      : please set \"BOOST_ROOT\" variable to the root directory of
-      your boost installation.  Searched in:
-      : $(boostbook-dir:J="
-") ;
-  }    
+  check-boostbook-dir $(boostbook-dir) ;
+  check-docbook-xsl-dir ;
+  check-docbook-dtd-dir ;
+  check-boostbook-xsl-dir ;
+  check-boostbook-dtd-dir ; 
 }
 
 rule xsl-dir
 {
+  lock-config ;
   return $(.boostbook-xsl-dir) ;
 }
 
 rule dtd-dir
 {
+  lock-config ;
   return $(.boostbook-dtd-dir) ;
 }
 
 rule docbook-xsl-dir
 {
+  lock-config ;
   return $(.docbook-xsl-dir) ;
 }
 
 rule docbook-dtd-dir
 {
+  lock-config ;
   return $(.docbook-dtd-dir) ;
 }
 
 rule dtdxml-to-boostbook ( target : source : properties * )
 {
+  lock-config ;
   xslt $(target) : $(source) "$(.boostbook-xsl-dir)/dtd/dtd2boostbook.xsl" 
                  : $(properties) ;
 }
 
 rule boostbook-to-docbook ( target : source : properties * )
 {
+  lock-config ;
   local stylesheet = [ path.native $(.boostbook-xsl-dir)/docbook.xsl ] ;
   xslt $(target) : $(source) $(stylesheet) : $(properties) ;
 }
 
 rule docbook-to-onehtml ( target : source : properties * )
 {
+  lock-config ;
   local stylesheet = [ path.native $(.boostbook-xsl-dir)/html-single.xsl ] ;
   xslt $(target) : $(source) $(stylesheet) : $(properties) ;
 }
 
 rule docbook-to-htmldir ( target : source : properties * )
 {
+  lock-config ;
   local stylesheet = [ path.native $(.boostbook-xsl-dir)/html.xsl ] ;
   xslt-dir $(target) : $(source) $(stylesheet) : $(properties) : html ;
 }
 
 rule docbook-to-xhtmldir ( target : source : properties * )
 {
+  lock-config ;
   local stylesheet = [ path.native $(.boostbook-xsl-dir)/xhtml.xsl ] ;
   xslt-dir $(target) : $(source) $(stylesheet) : $(properties) : xhtml ;
 }
 
 rule docbook-to-htmlhelp ( target : source : properties * )
 {
+  lock-config ;
   local stylesheet = [ path.native $(.boostbook-xsl-dir)/html-help.xsl ] ;
   xslt-dir $(target) : $(source) $(stylesheet) : $(properties) : htmlhelp ;
 }
 
 rule docbook-to-manpages ( target : source : properties * )
 {
+  lock-config ;
   local stylesheet = [ path.native $(.boostbook-xsl-dir)/manpages.xsl ] ;
   xslt-dir $(target) : $(source) $(stylesheet) : $(properties) : man ;
 }
 
 rule docbook-to-fo ( target : source : properties * )
 {
+  lock-config ;
   local stylesheet = [ path.native $(.boostbook-xsl-dir)/fo.xsl ] ;
   xslt $(target) : $(source) $(stylesheet) : $(properties) ;
 }
@@ -598,6 +714,7 @@ type.set-scanner XML : xinclude-scanner ;
 
 rule boostbook-to-tests ( target : source : properties * )
 {
+  lock-config ;
   local boost_root = [ modules.peek : BOOST_ROOT ] ;
   local native-path =
     [ path.native [ path.join $(.boostbook-xsl-dir) testing Jamfile ] ] ;