diff --git a/src/mame/machine/wpc.c b/src/mame/machine/wpc.c
index 76861317d28..dd1eef542a4 100644
--- a/src/mame/machine/wpc.c
+++ b/src/mame/machine/wpc.c
@@ -47,6 +47,7 @@ void wpc_device::device_reset()
 	m_memprotect = 0;
 	m_dmd_irqsrc = false;
 	m_snd_irqsrc = false;
+	m_alpha_pos = 0;
 }
 
 void wpc_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)