diff -Naur docbook-xsl-1.79.2/lib/lib.xsl docbook-xsl-1.79.2.new/lib/lib.xsl
--- docbook-xsl-1.79.2/lib/lib.xsl	2016-12-09 23:41:39.000000000 +0100
+++ docbook-xsl-1.79.2.new/lib/lib.xsl	2017-09-22 14:21:56.000000000 +0200
@@ -6,7 +6,11 @@
 
      This module implements DTD-independent functions
 
-     ******************************************************************** --><xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+     ******************************************************************** -->
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+                xmlns:str="http://exslt.org/strings"
+                exclude-result-prefixes="str"
+                version="1.0">
 
 <xsl:template name="dot.count">
   <!-- Returns the number of "." characters in a string -->
@@ -52,6 +56,9 @@
   <xsl:param name="replacement"/>
 
   <xsl:choose>
+    <xsl:when test="function-available('str:replace')">
+      <xsl:value-of select="str:replace($string, string($target), string($replacement))"/>
+    </xsl:when>
     <xsl:when test="contains($string, $target)">
       <xsl:variable name="rest">
         <xsl:call-template name="string.subst">