diff --git a/include/mgba/gba/interface.h b/include/mgba/gba/interface.h
index b698f4030..f83f9e717 100644
--- a/include/mgba/gba/interface.h
+++ b/include/mgba/gba/interface.h
@@ -118,6 +118,7 @@ struct GBASIODriver {
 	int (*connectedDevices)(struct GBASIODriver* driver);
 	int (*deviceId)(struct GBASIODriver* driver);
 	uint16_t (*writeSIOCNT)(struct GBASIODriver* driver, uint16_t value);
+	uint16_t (*writeRCNT)(struct GBASIODriver* driver, uint16_t value);
 };
 
 enum GBASIOBattleChipGateFlavor {
diff --git a/src/gba/extra/battlechip.c b/src/gba/extra/battlechip.c
index b71b4e33e..4070626d8 100644
--- a/src/gba/extra/battlechip.c
+++ b/src/gba/extra/battlechip.c
@@ -51,6 +51,7 @@ void GBASIOBattlechipGateCreate(struct GBASIOBattlechipGate* gate) {
 	gate->d.handlesMode = GBASIOBattlechipGateHandlesMode;
 	gate->d.connectedDevices = GBASIOBattlechipGateConnectedDevices;
 	gate->d.deviceId = NULL;
+	gate->d.writeRCNT = NULL;
 
 	gate->event.context = gate;
 	gate->event.callback = _battlechipTransferEvent;
diff --git a/src/gba/sio.c b/src/gba/sio.c
index 68b8fcb48..14edd7b7a 100644
--- a/src/gba/sio.c
+++ b/src/gba/sio.c
@@ -193,6 +193,10 @@ void GBASIOWriteRCNT(struct GBASIO* sio, uint16_t value) {
 	sio->rcnt &= 0xF;
 	sio->rcnt |= value & ~0xF;
 	_switchMode(sio);
+	if (sio->activeDriver && sio->activeDriver->writeRCNT) {
+		sio->rcnt &= 0xC000;
+		sio->rcnt |= sio->activeDriver->writeRCNT(sio->activeDriver, value) & 0x01FF;
+	}
 }
 
 void GBASIOWriteSIOCNT(struct GBASIO* sio, uint16_t value) {
@@ -278,8 +282,6 @@ uint16_t GBASIOWriteRegister(struct GBASIO* sio, uint32_t address, uint16_t valu
 		default:
 			mLOG(GBA_SIO, DEBUG, "JOY write: Unknown reg %03X <- %04X", address, value);
 			break;
-		case GBA_REG_RCNT:
-			break;
 		}
 		break;
 	case GBA_SIO_NORMAL_8:
@@ -290,8 +292,6 @@ uint16_t GBASIOWriteRegister(struct GBASIO* sio, uint32_t address, uint16_t valu
 		default:
 			mLOG(GBA_SIO, DEBUG, "NORMAL8 %i write: Unknown reg %03X <- %04X", id, address, value);
 			break;
-		case GBA_REG_RCNT:
-			break;
 		}
 		break;
 	case GBA_SIO_NORMAL_32:
@@ -305,8 +305,6 @@ uint16_t GBASIOWriteRegister(struct GBASIO* sio, uint32_t address, uint16_t valu
 		default:
 			mLOG(GBA_SIO, DEBUG, "NORMAL32 %i write: Unknown reg %03X <- %04X", id, address, value);
 			break;
-		case GBA_REG_RCNT:
-			break;
 		}
 		break;
 	case GBA_SIO_MULTI:
@@ -317,8 +315,6 @@ uint16_t GBASIOWriteRegister(struct GBASIO* sio, uint32_t address, uint16_t valu
 		default:
 			mLOG(GBA_SIO, DEBUG, "MULTI %i write: Unknown reg %03X <- %04X", id, address, value);
 			break;
-		case GBA_REG_RCNT:
-			break;
 		}
 		break;
 	default:
diff --git a/src/gba/sio/dolphin.c b/src/gba/sio/dolphin.c
index 039f9b528..f7aad747b 100644
--- a/src/gba/sio/dolphin.c
+++ b/src/gba/sio/dolphin.c
@@ -41,6 +41,7 @@ void GBASIODolphinCreate(struct GBASIODolphin* dol) {
 	dol->d.handlesMode = GBASIODolphinHandlesMode;
 	dol->d.connectedDevices = GBASIODolphinConnectedDevices;
 	dol->d.deviceId = NULL;
+	dol->d.writeSIOCNT = NULL;
 	dol->event.context = dol;
 	dol->event.name = "GB SIO Lockstep";
 	dol->event.callback = GBASIODolphinProcessEvents;
diff --git a/src/gba/sio/gbp.c b/src/gba/sio/gbp.c
index 7aeef1b0b..f7b3747a1 100644
--- a/src/gba/sio/gbp.c
+++ b/src/gba/sio/gbp.c
@@ -54,6 +54,7 @@ void GBASIOPlayerInit(struct GBASIOPlayer* gbp) {
 	gbp->d.handlesMode = _gbpSioHandlesMode;
 	gbp->d.connectedDevices = _gbpSioConnectedDevices;
 	gbp->d.deviceId = NULL;
+	gbp->d.writeRCNT = NULL;
 	gbp->event.context = gbp;
 	gbp->event.name = "GBA SIO Game Boy Player";
 	gbp->event.callback = _gbpSioProcessEvents;
diff --git a/src/gba/sio/lockstep.c b/src/gba/sio/lockstep.c
index 526d83575..30092c3ec 100644
--- a/src/gba/sio/lockstep.c
+++ b/src/gba/sio/lockstep.c
@@ -47,6 +47,7 @@ void GBASIOLockstepNodeCreate(struct GBASIOLockstepNode* node) {
 	node->d.connectedDevices = GBASIOLockstepNodeConnectedDevices;
 	node->d.deviceId = GBASIOLockstepNodeDeviceId;
 	node->d.writeSIOCNT = NULL;
+	node->d.writeRCNT = NULL;
 }
 
 bool GBASIOLockstepAttachNode(struct GBASIOLockstep* lockstep, struct GBASIOLockstepNode* node) {