diff --git a/doc/src/sgml/stylesheet-common.xsl b/doc/src/sgml/stylesheet-common.xsl
index 5db44a846f3..a2e3db67a32 100644
--- a/doc/src/sgml/stylesheet-common.xsl
+++ b/doc/src/sgml/stylesheet-common.xsl
@@ -43,6 +43,13 @@
 <xsl:param name="variablelist.term.separator"></xsl:param>
 <xsl:param name="xref.with.number.and.title" select="0"></xsl:param>
 
+<!--
+  This is the default setting, but putting it here makes sure the variable
+  exists even with older (<1.79) stylesheet versions, because it is used in
+  our customization layer.
+-->
+<xsl:param name="autolink.index.see" select="1"/>
+
 
 <!-- Change display of some elements -->
 
diff --git a/doc/src/sgml/stylesheet-fo.xsl b/doc/src/sgml/stylesheet-fo.xsl
index aff717ddbc7..3a4a88a7288 100644
--- a/doc/src/sgml/stylesheet-fo.xsl
+++ b/doc/src/sgml/stylesheet-fo.xsl
@@ -147,6 +147,10 @@
 
 <!-- from fo/autoidx.xsl -->
 
+<xsl:key name="primaryonly"
+         match="indexterm"
+         use="normalize-space(primary)"/>
+
 <xsl:template match="indexterm" mode="index-primary">
   <xsl:param name="scope" select="."/>
   <xsl:param name="role" select="''"/>
diff --git a/doc/src/sgml/stylesheet-html-common.xsl b/doc/src/sgml/stylesheet-html-common.xsl
index 7f541c09885..9dcf96c02e5 100644
--- a/doc/src/sgml/stylesheet-html-common.xsl
+++ b/doc/src/sgml/stylesheet-html-common.xsl
@@ -441,6 +441,10 @@ set       toc,title
 
 <!-- from html/autoidx.xsl -->
 
+<xsl:key name="primaryonly"
+         match="indexterm"
+         use="normalize-space(primary)"/>
+
 <xsl:template match="indexterm" mode="index-primary">
   <xsl:param name="scope" select="."/>
   <xsl:param name="role" select="''"/>