diff --git a/src/camel/camel-folder-search.c b/src/camel/camel-folder-search.c
index e240caa..f6f908c 100644
--- a/src/camel/camel-folder-search.c
+++ b/src/camel/camel-folder-search.c
@@ -1046,6 +1046,7 @@ folder_search_match_threads (CamelSExp *sexp,
 		g_free (error_msg);
 	}
 
+	/* no thread matching, the earlier result is already complete */
 	if (type == 0)
 		return r;
 
@@ -1065,11 +1066,14 @@ folder_search_match_threads (CamelSExp *sexp,
 	}
 
 	results = g_hash_table_new (g_str_hash, g_str_equal);
+	/* iterate every message matching the rest of the search terms */
 	for (i = 0; i < r->value.ptrarray->len && !g_cancellable_is_cancelled (search->priv->cancellable); i++) {
 		CamelFolderThreadNode *node, *scan;
 
-		if (type != 4)
+		if (type != 4) {
+			/* the matched message itself will always be part of the returned result unless in "(match-thread single)" mode */
 			g_hash_table_insert (results, g_ptr_array_index (r->value.ptrarray, i), GINT_TO_POINTER (1));
+		}
 
 		node = g_hash_table_lookup (p->threads_hash, (gchar *) g_ptr_array_index (r->value.ptrarray, i));
 		if (node == NULL) /* this shouldn't happen but why cry over spilt milk */
@@ -1080,14 +1084,14 @@ folder_search_match_threads (CamelSExp *sexp,
 			if (node->child == NULL && node->parent == NULL)
 				g_hash_table_insert (results, (gchar *) camel_message_info_get_uid (node->message), GINT_TO_POINTER (1));
 		} else {
-			if (type == 3) {
+			if (type == 3) { /* add the parents of the matched message */
 				scan = node;
 				/* coverity[check_after_deref] */
 				while (scan && scan->parent) {
 					scan = scan->parent;
 					g_hash_table_insert (results, (gchar *) camel_message_info_get_uid (scan->message), GINT_TO_POINTER (1));
 				}
-			} else if (type == 1) {
+			} else if (type == 1) {	/* get the thread root message, we will add all the descendants below */
 				while (node != NULL && node->parent)
 					node = node->parent;
 			}