diff --git a/notmuch-reply.c b/notmuch-reply.c
index eb074055..c2d7402d 100644
--- a/notmuch-reply.c
+++ b/notmuch-reply.c
@@ -538,13 +538,12 @@ create_reply_message(void *ctx,
     g_mime_object_set_header (GMIME_OBJECT (reply), "In-Reply-To", in_reply_to);
 
     orig_references = notmuch_message_get_header (message, "references");
-    if (!orig_references)
-	/* Treat errors like missing References headers. */
-	orig_references = "";
-    references = talloc_asprintf (ctx, "%s%s%s",
-				  *orig_references ? orig_references : "",
-				  *orig_references ? " " : "",
-				  in_reply_to);
+    if (orig_references && *orig_references)
+	references = talloc_asprintf (ctx, "%s %s", orig_references,
+				      in_reply_to);
+    else
+	references = talloc_strdup (ctx, in_reply_to);
+
     g_mime_object_set_header (GMIME_OBJECT (reply), "References", references);
 
     from_addr = add_recipients_from_message (reply, config,