diff --git a/src/nvr_at.c b/src/nvr_at.c
index 2e04ddc6f..09ce1e57e 100644
--- a/src/nvr_at.c
+++ b/src/nvr_at.c
@@ -637,7 +637,7 @@ nvr_reg_write(uint16_t reg, uint8_t val, void *priv)
 
         case 0x39:
             if (machines[machine].init == machine_at_bx6_init)
-                nvr_reg_common_write(reg, val | 0x08, nvr, local);
+                nvr_reg_common_write(reg, val | 0x09, nvr, local);
             else
                 nvr_reg_common_write(reg, val, nvr, local);
             break;
@@ -805,7 +805,7 @@ nvr_read(uint16_t addr, void *priv)
                 if (!(local->lock[local->addr[addr_id]] & 0x02)) {
                     ret = nvr->regs[local->addr[addr_id]];
                     if (machines[machine].init == machine_at_bx6_init)
-                        ret |= 0x08;
+                        ret |= 0x09;
                 }
                 break;