diff --git a/src/mame/nec/pc9801.cpp b/src/mame/nec/pc9801.cpp
index 0b0552a401b..07e7a48b3c5 100644
--- a/src/mame/nec/pc9801.cpp
+++ b/src/mame/nec/pc9801.cpp
@@ -2382,12 +2382,12 @@ void pc9801_state::pc9801_common(machine_config &config)
 	SCREEN(config, m_screen, SCREEN_TYPE_RASTER);
 	m_screen->set_raw(21.0526_MHz_XTAL, 848, 0, 640, 440, 0, 400);
 	m_screen->set_screen_update(FUNC(pc9801_state::screen_update));
-	m_screen->screen_vblank().set(FUNC(pc9801_state::vrtc_irq));
 
 	UPD7220(config, m_hgdc[0], 21.0526_MHz_XTAL / 8, "screen");
 	m_hgdc[0]->set_addrmap(0, &pc9801_state::upd7220_1_map);
 	m_hgdc[0]->set_draw_text(FUNC(pc9801_state::hgdc_draw_text));
 	m_hgdc[0]->vsync_wr_callback().set(m_hgdc[1], FUNC(upd7220_device::ext_sync_w));
+	m_hgdc[0]->vsync_wr_callback().append(FUNC(pc9801_state::vrtc_irq));
 
 	UPD7220(config, m_hgdc[1], 21.0526_MHz_XTAL / 8, "screen");
 	m_hgdc[1]->set_addrmap(0, &pc9801_state::upd7220_2_map);