diff --git a/include/mgba/internal/gba/sio.h b/include/mgba/internal/gba/sio.h
index 260772f55..a546017dc 100644
--- a/include/mgba/internal/gba/sio.h
+++ b/include/mgba/internal/gba/sio.h
@@ -85,6 +85,8 @@ void GBASIOWriteRCNT(struct GBASIO* sio, uint16_t value);
 void GBASIOWriteSIOCNT(struct GBASIO* sio, uint16_t value);
 uint16_t GBASIOWriteRegister(struct GBASIO* sio, uint32_t address, uint16_t value);
 
+void GBASIOMultiplayerFinishTransfer(struct GBASIO* sio, uint16_t data[4], uint32_t cyclesLate);
+
 int GBASIOJOYSendCommand(struct GBASIODriver* sio, enum GBASIOJOYCommand command, uint8_t* data);
 
 CXX_GUARD_END
diff --git a/src/gba/extra/battlechip.c b/src/gba/extra/battlechip.c
index 841981fb7..12750f67b 100644
--- a/src/gba/extra/battlechip.c
+++ b/src/gba/extra/battlechip.c
@@ -131,11 +131,6 @@ void _battlechipTransferEvent(struct mTiming* timing, void* user, uint32_t cycle
 
 	uint16_t cmd = gate->d.p->p->memory.io[GBA_REG(SIOMLT_SEND)];
 	uint16_t reply = 0xFFFF;
-	gate->d.p->p->memory.io[GBA_REG(SIOMULTI0)] = cmd;
-	gate->d.p->p->memory.io[GBA_REG(SIOMULTI2)] = 0xFFFF;
-	gate->d.p->p->memory.io[GBA_REG(SIOMULTI3)] = 0xFFFF;
-	gate->d.p->siocnt = GBASIOMultiplayerClearBusy(gate->d.p->siocnt);
-	gate->d.p->siocnt = GBASIOMultiplayerSetId(gate->d.p->siocnt, 0);
 
 	mLOG(GBA_BATTLECHIP, DEBUG, "Game: %04X (%i)", cmd, gate->state);
 
@@ -168,7 +163,7 @@ void _battlechipTransferEvent(struct mTiming* timing, void* user, uint32_t cycle
 		case 0xA3D0:
 		// EXE 4
 		case 0xA6C0:
-		mLOG(GBA_BATTLECHIP, DEBUG, "Resync detected");
+			mLOG(GBA_BATTLECHIP, DEBUG, "Resync detected");
 			gate->state = BATTLECHIP_STATE_SYNC;
 			break;
 		}
@@ -213,9 +208,8 @@ void _battlechipTransferEvent(struct mTiming* timing, void* user, uint32_t cycle
 	mLOG(GBA_BATTLECHIP, DEBUG, "Gate: %04X (%i)", reply, gate->state);
 	++gate->state;
 
-	gate->d.p->p->memory.io[GBA_REG(SIOMULTI1)] = reply;
-
-	if (GBASIOMultiplayerIsIrq(gate->d.p->siocnt)) {
-		GBARaiseIRQ(gate->d.p->p, GBA_IRQ_SIO, cyclesLate);
-	}
+	uint16_t data[4] = {
+		cmd, reply, 0xFFFF, 0xFFFF
+	};
+	GBASIOMultiplayerFinishTransfer(gate->d.p, data, cyclesLate);
 }
diff --git a/src/gba/sio.c b/src/gba/sio.c
index 4eb9cfa3c..cdccf1ea3 100644
--- a/src/gba/sio.c
+++ b/src/gba/sio.c
@@ -318,6 +318,23 @@ uint16_t GBASIOWriteRegister(struct GBASIO* sio, uint32_t address, uint16_t valu
 	return value;
 }
 
+void GBASIOMultiplayerFinishTransfer(struct GBASIO* sio, uint16_t data[4], uint32_t cyclesLate) {
+	int id = 0;
+	if (sio->activeDriver && sio->activeDriver->deviceId) {
+		id = sio->activeDriver->deviceId(sio->activeDriver);
+	}
+	sio->p->memory.io[GBA_REG(SIOMULTI0)] = data[0];
+	sio->p->memory.io[GBA_REG(SIOMULTI1)] = data[1];
+	sio->p->memory.io[GBA_REG(SIOMULTI2)] = data[2];
+	sio->p->memory.io[GBA_REG(SIOMULTI3)] = data[3];
+	sio->rcnt |= 1;
+	sio->siocnt = GBASIOMultiplayerClearBusy(sio->siocnt);
+	sio->siocnt = GBASIOMultiplayerSetId(sio->siocnt, id);
+	if (GBASIOMultiplayerIsIrq(sio->siocnt)) {
+		GBARaiseIRQ(sio->p, GBA_IRQ_SIO, cyclesLate);
+	}
+}
+
 int GBASIOJOYSendCommand(struct GBASIODriver* sio, enum GBASIOJOYCommand command, uint8_t* data) {
 	switch (command) {
 	case JOY_RESET:
diff --git a/src/gba/sio/lockstep.c b/src/gba/sio/lockstep.c
index 9709f633b..b7f5752b4 100644
--- a/src/gba/sio/lockstep.c
+++ b/src/gba/sio/lockstep.c
@@ -280,16 +280,7 @@ static void _finishTransfer(struct GBASIOLockstepNode* node) {
 	struct GBASIO* sio = node->d.p;
 	switch (node->mode) {
 	case GBA_SIO_MULTI:
-		sio->p->memory.io[GBA_REG(SIOMULTI0)] = node->p->multiRecv[0];
-		sio->p->memory.io[GBA_REG(SIOMULTI1)] = node->p->multiRecv[1];
-		sio->p->memory.io[GBA_REG(SIOMULTI2)] = node->p->multiRecv[2];
-		sio->p->memory.io[GBA_REG(SIOMULTI3)] = node->p->multiRecv[3];
-		sio->rcnt |= 1;
-		sio->siocnt = GBASIOMultiplayerClearBusy(sio->siocnt);
-		sio->siocnt = GBASIOMultiplayerSetId(sio->siocnt, node->id);
-		if (GBASIOMultiplayerIsIrq(sio->siocnt)) {
-			GBARaiseIRQ(sio->p, GBA_IRQ_SIO, 0);
-		}
+		GBASIOMultiplayerFinishTransfer(sio, node->p->multiRecv, 0);
 		break;
 	case GBA_SIO_NORMAL_8:
 		// TODO