diff --git a/src/emu/machine/8042kbdc.c b/src/emu/machine/8042kbdc.c
index cfca188bad5..c497d818f33 100644
--- a/src/emu/machine/8042kbdc.c
+++ b/src/emu/machine/8042kbdc.c
@@ -227,6 +227,8 @@ void kbdc8042_device::device_start()
 	m_output_buffer_empty_cb.resolve_safe();
 	m_speaker_cb.resolve();
 	m_operation_write_state = 0; /* first write to 0x60 might occur before anything can set this */
+	memset(&m_keyboard, 0x00, sizeof(m_keyboard));
+	memset(&m_mouse, 0x00, sizeof(m_mouse));
 }
 
 /*-------------------------------------------------