diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 6186648ccaf..e55700f35b8 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -8378,9 +8378,11 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         displayed in <link linkend="monitoring-pg-stat-database-view">
         <structname>pg_stat_database</structname></link>,
         <link linkend="monitoring-pg-stat-io-view">
-        <structname>pg_stat_io</structname></link>, in the output of the
+        <structname>pg_stat_io</structname></link> (if <varname>object</varname>
+        is not <literal>wal</literal>), in the output of the
         <link linkend="pg-stat-get-backend-io">
-        <function>pg_stat_get_backend_io()</function></link> function, in the
+        <function>pg_stat_get_backend_io()</function></link> function (if
+        <varname>object</varname> is not <literal>wal</literal>), in the
         output of <xref linkend="sql-explain"/> when the <literal>BUFFERS</literal>
         option is used, in the output of <xref linkend="sql-vacuum"/> when
         the <literal>VERBOSE</literal> option is used, by autovacuum
@@ -8411,7 +8413,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         <structname>pg_stat_io</structname></link> for the
         <varname>object</varname> <literal>wal</literal> and in the output of
         the <link linkend="pg-stat-get-backend-io">
-        <function>pg_stat_get_backend_io()</function></link> function.
+        <function>pg_stat_get_backend_io()</function></link> function for the
+        <varname>object</varname> <literal>wal</literal>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.
        </para>