diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index cd0c4fa084c..ba51ac2cecf 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3312,6 +3312,7 @@ include_dir 'conf.d'
         was compiled with <option>--with-lz4</option>) and
         <literal>zstd</literal> (if <productname>PostgreSQL</productname>
         was compiled with <option>--with-zstd</option>).
+        The value <literal>on</literal> is a historical spelling of <literal>pglz</literal>.
         The default value is <literal>off</literal>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8ffcdf7b16..172d70051f0 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -231,7 +231,7 @@
 #wal_log_hints = off			# also do full page writes of non-critical updates
 					# (change requires restart)
 #wal_compression = off			# enables compression of full-page writes;
-					# off, pglz, lz4, zstd, or on
+					# off, pglz (or "on"), lz4, or zstd
 #wal_init_zero = on			# zero-fill new WAL files
 #wal_recycle = on			# recycle WAL files
 #wal_buffers = -1			# min 32kB, -1 sets based on shared_buffers