diff --git a/doc/src/sgml/func/func-string.sgml b/doc/src/sgml/func/func-string.sgml
index 7ad1436e5f8..646b5d6d8c4 100644
--- a/doc/src/sgml/func/func-string.sgml
+++ b/doc/src/sgml/func/func-string.sgml
@@ -173,7 +173,7 @@
         <returnvalue>integer</returnvalue>
        </para>
        <para role="func_signature">
-        <indexterm>
+        <indexterm id="function-character-length">
          <primary>character_length</primary>
         </indexterm>
         <function>character_length</function> ( <type>text</type> )
@@ -208,7 +208,7 @@
 
       <row>
        <entry role="func_table_entry"><para role="func_signature">
-        <indexterm>
+        <indexterm id="function-lpad">
          <primary>lpad</primary>
         </indexterm>
         <function>lpad</function> ( <parameter>string</parameter> <type>text</type>,
@@ -277,7 +277,7 @@
 
       <row>
        <entry role="func_table_entry"><para role="func_signature">
-        <indexterm>
+        <indexterm id="function-octet-length">
          <primary>octet_length</primary>
         </indexterm>
         <function>octet_length</function> ( <type>text</type> )
@@ -1334,7 +1334,7 @@
 
       <row>
        <entry role="func_table_entry"><para role="func_signature">
-        <indexterm>
+        <indexterm id="function-string-to-table">
          <primary>string_to_table</primary>
         </indexterm>
         <function>string_to_table</function> ( <parameter>string</parameter> <type>text</type>, <parameter>delimiter</parameter> <type>text</type> <optional>, <parameter>null_string</parameter> <type>text</type> </optional> )
diff --git a/src/tools/pgindent/pgperltidy b/src/tools/pgindent/pgperltidy
index 6af27d21d55..6fac758665a 100755
--- a/src/tools/pgindent/pgperltidy
+++ b/src/tools/pgindent/pgperltidy
@@ -7,6 +7,12 @@ set -e
 # set this to override default perltidy program:
 PERLTIDY=${PERLTIDY:-perltidy}
 
+PERLTIDY_VERSION=20230309
+if ! $PERLTIDY -v | grep -q $PERLTIDY_VERSION; then
+	echo "error: pgperltidy requires perltidy v$PERLTIDY_VERSION"
+	exit 1
+fi
+
 . src/tools/perlcheck/find_perl_files
 
 find_perl_files "$@" | xargs $PERLTIDY --profile=src/tools/pgindent/perltidyrc