diff --git a/notmuch-client.h b/notmuch-client.h
index b11caff8..ae9344b2 100644
--- a/notmuch-client.h
+++ b/notmuch-client.h
@@ -71,13 +71,9 @@ struct notmuch_show_params;
 
 typedef struct notmuch_show_format {
     struct sprinter *(*new_sprinter) (const void *ctx, FILE *stream);
-    const char *message_set_start;
     notmuch_status_t (*part) (const void *ctx, struct sprinter *sprinter,
 			      struct mime_node *node, int indent,
 			      const struct notmuch_show_params *params);
-    const char *message_set_sep;
-    const char *message_set_end;
-    const char *null_message;
 } notmuch_show_format_t;
 
 typedef struct notmuch_crypto {
diff --git a/notmuch-show.c b/notmuch-show.c
index 89bf2e76..35562934 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -37,11 +37,7 @@ format_part_json_entry (const void *ctx, sprinter_t *sp, mime_node_t *node,
 
 static const notmuch_show_format_t format_json = {
     .new_sprinter = sprinter_json_create,
-    .message_set_start = "[",
     .part = format_part_json_entry,
-    .message_set_sep = ", ",
-    .message_set_end = "]",
-    .null_message = "null"
 };
 
 static notmuch_status_t