diff --git a/src/devices/machine/at_keybc.cpp b/src/devices/machine/at_keybc.cpp
index 98b5b5f6ca1..d4beb3ce68e 100644
--- a/src/devices/machine/at_keybc.cpp
+++ b/src/devices/machine/at_keybc.cpp
@@ -484,6 +484,8 @@ void ps2_keyboard_controller_device::device_start()
 {
 	at_kbc_device_base::device_start();
 
+	m_aux_irq_timer = timer_alloc(FUNC(ps2_keyboard_controller_device::set_aux_irq_timer_callback), this);
+
 	save_item(NAME(m_aux_irq));
 	save_item(NAME(m_aux_clk_in));
 	save_item(NAME(m_aux_clk_out));
@@ -552,6 +554,17 @@ void ps2_keyboard_controller_device::p2_w(uint8_t data)
 	if (BIT(data & ~m_p2_data, 4))
 		set_kbd_irq(1U);
 	if (BIT(data & ~m_p2_data, 5))
-		set_aux_irq(1U);
+	{
+		// HACK: delay raising the aux irq until compaq queues the data
+		if (m_mcu->pcbase() == 0x7ba)
+			m_aux_irq_timer->adjust(attotime::from_hz(clock() / 16));
+		else
+			set_aux_irq(1U);
+	}
 	m_p2_data = data;
 }
+
+TIMER_CALLBACK_MEMBER(ps2_keyboard_controller_device::set_aux_irq_timer_callback)
+{
+	set_aux_irq(1U);
+}
diff --git a/src/devices/machine/at_keybc.h b/src/devices/machine/at_keybc.h
index a65c1a61e72..784ecb803b5 100644
--- a/src/devices/machine/at_keybc.h
+++ b/src/devices/machine/at_keybc.h
@@ -144,11 +144,13 @@ private:
 	// internal sync helpers
 	TIMER_CALLBACK_MEMBER(set_aux_clk_in);
 	TIMER_CALLBACK_MEMBER(set_aux_data_in);
+	TIMER_CALLBACK_MEMBER(set_aux_irq_timer_callback);
 
 	// MCU I/O handlers
 	uint8_t p1_r();
 	void p2_w(uint8_t data);
 
+	emu_timer* m_aux_irq_timer;
 	devcb_write_line m_aux_irq_cb;
 	devcb_write_line m_aux_clk_cb, m_aux_data_cb;