diff --git a/src/mame/drivers/namcos22.c b/src/mame/drivers/namcos22.c
index 7b1c756c0ed..5cdaa299a86 100644
--- a/src/mame/drivers/namcos22.c
+++ b/src/mame/drivers/namcos22.c
@@ -4611,7 +4611,7 @@ ROM_START( aquajet )
         ROM_LOAD( "aj1ptru2.15f", 0x500000, 0x080000, CRC(91ffbb77) SHA1(fbfe7d32ef22037f7190d1b8263b5e8c55f2d892) )
         ROM_LOAD( "aj1ptru3.14f", 0x580000, 0x080000, CRC(d83d8d42) SHA1(e1561ce4538b01db92b7e645ad008cd1a2ddaf8a) )
 
-	ROM_REGION( 0xa00000, "c352", 0 ) /* sound samples */
+	ROM_REGION( 0x1000000, "c352", 0 ) /* sound samples */
         ROM_LOAD( "aj1wavea.2l",  0x000000, 0x400000, CRC(8c72ea59) SHA1(3ae8dbd8baae08f1daab2b218932ba9d9451231d) )
         ROM_LOAD( "aj1waveb.1l",  0x800000, 0x400000, CRC(ab5a457f) SHA1(c34531fd574eb0c3e78fc31a9af8658df3446adc) )
 ROM_END