diff --git a/notmuch-client.h b/notmuch-client.h
index 1dbd987d..57daa9a2 100644
--- a/notmuch-client.h
+++ b/notmuch-client.h
@@ -54,6 +54,27 @@
 #define STRINGIFY(s) STRINGIFY_(s)
 #define STRINGIFY_(s) #s
 
+typedef struct notmuch_show_format {
+    const char *message_set_start;
+    const char *message_start;
+    void (*message) (const void *ctx,
+		     notmuch_message_t *message,
+		     int indent);
+    const char *header_start;
+    void (*header) (const void *ctx,
+		    notmuch_message_t *message);
+    const char *header_end;
+    const char *body_start;
+    void (*part) (GMimeObject *part,
+		  int *part_count,
+		  int first);
+    void (*part_end) (GMimeObject *part);
+    const char *body_end;
+    const char *message_end;
+    const char *message_set_sep;
+    const char *message_set_end;
+} notmuch_show_format_t;
+
 /* There's no point in continuing when we've detected that we've done
  * something wrong internally (as opposed to the user passing in a
  * bogus value).
@@ -133,8 +154,7 @@ query_string_from_args (void *ctx, int argc, char *argv[]);
 
 notmuch_status_t
 show_message_body (const char *filename,
-		   void (*show_part) (GMimeObject *part, int *part_count, int first),
-		   void (*show_part_end) (GMimeObject *part));
+		   const notmuch_show_format_t *format);
 
 notmuch_status_t
 show_one_part (const char *filename, int part);
diff --git a/notmuch-reply.c b/notmuch-reply.c
index 71edb662..064d27e0 100644
--- a/notmuch-reply.c
+++ b/notmuch-reply.c
@@ -24,6 +24,20 @@
 #include "gmime-filter-reply.h"
 #include "gmime-filter-headers.h"
 
+static void
+reply_part (GMimeObject *part,
+	    unused (int *part_count),
+	    unused (int first));
+
+static const notmuch_show_format_t format_reply = {
+    NULL,
+	NULL, NULL,
+	    NULL, NULL, NULL,
+	    NULL, reply_part, NULL, NULL,
+	NULL, NULL,
+    NULL
+};
+
 static void
 reply_part_content (GMimeObject *part)
 {
@@ -72,12 +86,13 @@ show_reply_headers (GMimeMessage *message)
 }
 
 static void
-reply_part (GMimeObject *part, int *part_count, unused (int first))
+reply_part (GMimeObject *part,
+	    unused (int *part_count),
+	    unused (int first))
 {
     GMimeContentDisposition *disposition;
     GMimeContentType *content_type;
 
-    (void) part_count;
     disposition = g_mime_object_get_content_disposition (part);
     if (disposition &&
 	strcmp (disposition->disposition, GMIME_DISPOSITION_ATTACHMENT) == 0)
@@ -447,6 +462,7 @@ notmuch_reply_format_default(void *ctx, notmuch_config_t *config, notmuch_query_
     notmuch_message_t *message;
     const char *subject, *from_addr = NULL;
     const char *in_reply_to, *orig_references, *references;
+    const notmuch_show_format_t *format = &format_reply;
 
     for (messages = notmuch_query_search_messages (query);
 	 notmuch_messages_valid (messages);
@@ -506,7 +522,7 @@ notmuch_reply_format_default(void *ctx, notmuch_config_t *config, notmuch_query_
 		notmuch_message_get_header (message, "from"));
 
 	show_message_body (notmuch_message_get_filename (message),
-			   reply_part, NULL);
+			   format);
 
 	notmuch_message_destroy (message);
     }
diff --git a/notmuch-show.c b/notmuch-show.c
index 7220dd97..20e54bcd 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -20,26 +20,6 @@
 
 #include "notmuch-client.h"
 
-typedef struct show_format {
-    const char *message_set_start;
-    const char *message_start;
-    void (*message) (const void *ctx,
-		     notmuch_message_t *message,
-		     int indent);
-    const char *header_start;
-    void (*header) (const void *ctx,
-		    notmuch_message_t *message);
-    const char *header_end;
-    const char *body_start;
-    void (*part) (GMimeObject *part,
-		  int *part_count, int first);
-    void (*part_end) (GMimeObject *part);
-    const char *body_end;
-    const char *message_end;
-    const char *message_set_sep;
-    const char *message_set_end;
-} show_format_t;
-
 static void
 format_message_text (unused (const void *ctx),
 		     notmuch_message_t *message,
@@ -56,7 +36,7 @@ format_part_text (GMimeObject *part,
 static void
 format_part_end_text (GMimeObject *part);
 
-static const show_format_t format_text = {
+static const notmuch_show_format_t format_text = {
     "",
 	"\fmessage{ ", format_message_text,
 	    "\fheader{\n", format_headers_text, "\fheader}\n",
@@ -81,7 +61,7 @@ format_part_json (GMimeObject *part,
 static void
 format_part_end_json (GMimeObject *part);
 
-static const show_format_t format_json = {
+static const notmuch_show_format_t format_json = {
     "[",
 	"{", format_message_json,
 	    ", \"headers\": {", format_headers_json, "}",
@@ -95,7 +75,7 @@ format_message_mbox (const void *ctx,
 		     notmuch_message_t *message,
 		     unused (int indent));
 
-static const show_format_t format_mbox = {
+static const notmuch_show_format_t format_mbox = {
     "",
         "", format_message_mbox,
             "", NULL, "",
@@ -515,7 +495,10 @@ format_part_end_json (GMimeObject *part)
 }
 
 static void
-show_message (void *ctx, const show_format_t *format, notmuch_message_t *message, int indent)
+show_message (void *ctx,
+	      const notmuch_show_format_t *format,
+	      notmuch_message_t *message,
+	      int indent)
 {
     fputs (format->message_start, stdout);
     if (format->message)
@@ -529,7 +512,7 @@ show_message (void *ctx, const show_format_t *format, notmuch_message_t *message
     fputs (format->body_start, stdout);
     if (format->part)
 	show_message_body (notmuch_message_get_filename (message),
-			   format->part, format->part_end);
+			   format);
     fputs (format->body_end, stdout);
 
     fputs (format->message_end, stdout);
@@ -537,7 +520,10 @@ show_message (void *ctx, const show_format_t *format, notmuch_message_t *message
 
 
 static void
-show_messages (void *ctx, const show_format_t *format, notmuch_messages_t *messages, int indent,
+show_messages (void *ctx,
+	       const notmuch_show_format_t *format,
+	       notmuch_messages_t *messages,
+	       int indent,
 	       notmuch_bool_t entire_thread)
 {
     notmuch_message_t *message;
@@ -631,7 +617,7 @@ do_show_raw (unused(void *ctx), notmuch_query_t *query)
 static int
 do_show (void *ctx,
 	 notmuch_query_t *query,
-	 const show_format_t *format,
+	 const notmuch_show_format_t *format,
 	 int entire_thread)
 {
     notmuch_threads_t *threads;
@@ -676,7 +662,7 @@ notmuch_show_command (void *ctx, unused (int argc), unused (char *argv[]))
     notmuch_query_t *query;
     char *query_string;
     char *opt;
-    const show_format_t *format = &format_text;
+    const notmuch_show_format_t *format = &format_text;
     int entire_thread = 0;
     int i;
     int raw = 0;
diff --git a/show-message.c b/show-message.c
index c206bddc..44ab8194 100644
--- a/show-message.c
+++ b/show-message.c
@@ -25,8 +25,7 @@
 static void
 show_message_part (GMimeObject *part,
 		   int *part_count,
-		   void (*show_part) (GMimeObject *part, int *part_count, int first),
-		   void (*show_part_end) (GMimeObject *part),
+		   const notmuch_show_format_t *format,
 		   int first)
 {
     if (GMIME_IS_MULTIPART (part)) {
@@ -34,15 +33,15 @@ show_message_part (GMimeObject *part,
 	int i;
 
 	*part_count = *part_count + 1;
-	(*show_part) (part, part_count, first);
+	format->part (part, part_count, first);
 
 	for (i = 0; i < g_mime_multipart_get_count (multipart); i++) {
 	    show_message_part (g_mime_multipart_get_part (multipart, i),
-			       part_count, show_part, show_part_end, i == 0);
+			       part_count, format, i == 0);
 	}
 
-	if (show_part_end)
-	    (*show_part_end) (part);
+	if (format->part_end)
+	    format->part_end (part);
 
 	return;
     }
@@ -53,7 +52,7 @@ show_message_part (GMimeObject *part,
 	mime_message = g_mime_message_part_get_message (GMIME_MESSAGE_PART (part));
 
 	show_message_part (g_mime_message_get_mime_part (mime_message),
-			   part_count, show_part, show_part_end, first);
+			   part_count, format, first);
 
 	return;
     }
@@ -66,15 +65,14 @@ show_message_part (GMimeObject *part,
 
     *part_count = *part_count + 1;
 
-    (*show_part) (part, part_count, first);
-    if (show_part_end)
-	(*show_part_end) (part);
+    format->part (part, part_count, first);
+    if (format->part_end)
+	format->part_end (part);
 }
 
 notmuch_status_t
 show_message_body (const char *filename,
-		   void (*show_part) (GMimeObject *part, int *part_count, int first),
-		   void (*show_part_end) (GMimeObject *part))
+		   const notmuch_show_format_t *format)
 {
     GMimeStream *stream = NULL;
     GMimeParser *parser = NULL;
@@ -98,7 +96,9 @@ show_message_body (const char *filename,
     mime_message = g_mime_parser_construct_message (parser);
 
     show_message_part (g_mime_message_get_mime_part (mime_message),
-		       &part_count, show_part, show_part_end, TRUE);
+		       &part_count,
+		       format,
+		       TRUE);
 
   DONE:
     if (mime_message)