diff --git a/src/emu/bus/rs232/keyboard.c b/src/emu/bus/rs232/keyboard.c
index da4672852ca..aee3527a726 100644
--- a/src/emu/bus/rs232/keyboard.c
+++ b/src/emu/bus/rs232/keyboard.c
@@ -4,6 +4,7 @@ serial_keyboard_device::serial_keyboard_device(const machine_config &mconfig, co
 	: generic_keyboard_device(mconfig, SERIAL_KEYBOARD, "Serial Keyboard", tag, owner, clock, "serial_keyboard", __FILE__),
 	device_serial_interface(mconfig, *this),
 	device_rs232_port_interface(mconfig, *this),
+	m_key_valid(false),
 	m_rs232_txbaud(*this, "RS232_TXBAUD"),
 	m_rs232_startbits(*this, "RS232_STARTBITS"),
 	m_rs232_databits(*this, "RS232_DATABITS"),
@@ -16,6 +17,7 @@ serial_keyboard_device::serial_keyboard_device(const machine_config &mconfig, de
 	: generic_keyboard_device(mconfig, type, name, tag, owner, clock, shortname, source),
 	device_serial_interface(mconfig, *this),
 	device_rs232_port_interface(mconfig, *this),
+	m_key_valid(false),
 	m_rs232_txbaud(*this, "RS232_TXBAUD"),
 	m_rs232_startbits(*this, "RS232_STARTBITS"),
 	m_rs232_databits(*this, "RS232_DATABITS"),