diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index a62d64eaa4..4a8410c849 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -4173,7 +4173,7 @@ static struct config_string ConfigureNamesString[] =
 		{"unix_socket_directories", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
 			gettext_noop("Sets the directories where Unix-domain sockets will be created."),
 			NULL,
-			GUC_SUPERUSER_ONLY
+			GUC_LIST_INPUT | GUC_SUPERUSER_ONLY
 		},
 		&Unix_socket_directories,
 #ifdef HAVE_UNIX_SOCKETS