diff --git a/core/filter.c b/core/filter.c
index 2956adf0..747b7309 100644
--- a/core/filter.c
+++ b/core/filter.c
@@ -7,6 +7,29 @@
 static GHashTable *filter_index = NULL;
 
 
+void __filter_copy(const struct set *lhs, struct set *rhs)
+{
+	GHashTableIter iter;
+	gpointer data;
+
+	g_hash_table_iter_init(&iter, lhs->s_set);
+	while (g_hash_table_iter_next(&iter, &data, NULL))
+		set_insert(rhs, GPOINTER_TO_UINT(data));
+}
+
+void __filter_inline_intersect(const struct set *lhs, struct set *rhs)
+{
+	GHashTableIter iter;
+	gpointer data;
+
+	g_hash_table_iter_init(&iter, rhs->s_set);
+	while (g_hash_table_iter_next(&iter, &data, NULL)) {
+		if (!set_has(lhs, GPOINTER_TO_UINT(data)))
+			g_hash_table_iter_remove(&iter);
+	}
+}
+
+
 void filter_init()
 {
 	filter_index = g_hash_table_new_full(g_str_hash, g_str_equal,
@@ -93,9 +116,9 @@ void filter_search(const gchar *text, struct set *res)
 		}
 
 		if (begin == 0)
-			set_copy(found, res);
+			__filter_copy(found, res);
 		else
-			set_inline_intersect(found, res);
+			__filter_inline_intersect(found, res);
 
 		c = g_utf8_next_char(c);
 		begin = ++end;