diff --git a/src/mess/drivers/pc9801.c b/src/mess/drivers/pc9801.c
index 49f03f1480f..69c7a239dba 100644
--- a/src/mess/drivers/pc9801.c
+++ b/src/mess/drivers/pc9801.c
@@ -2408,7 +2408,7 @@ static ADDRESS_MAP_START( pc9821_io, AS_IO, 32, pc9801_state )
 //  AM_RANGE(0x043d, 0x043d) ROM/RAM bank (NEC)
 	AM_RANGE(0x043c, 0x043f) AM_WRITE8(pc9801rs_bank_w,    0xffffffff) //ROM/RAM bank (EPSON)
 	AM_RANGE(0x0460, 0x0463) AM_READWRITE8(pc9821_window_bank_r,pc9821_window_bank_w, 0xffffffff)
-//  AM_RANGE(0x04a0, 0x04af) EGC
+	AM_RANGE(0x04a0, 0x04af) AM_WRITE16(egc_w, 0xffffffff)
 //  AM_RANGE(0x04be, 0x04be) FDC "RPM" register
 	AM_RANGE(0x0640, 0x064f) AM_DEVREADWRITE16("ide", ata_interface_device, read_cs0, write_cs0, 0xffffffff)
 	AM_RANGE(0x0740, 0x074f) AM_DEVREADWRITE16("ide", ata_interface_device, read_cs1, write_cs1, 0xffffffff)