diff --git a/src/gba/hardware.c b/src/gba/hardware.c
index a2e61c927..7d5a16d7a 100644
--- a/src/gba/hardware.c
+++ b/src/gba/hardware.c
@@ -27,7 +27,6 @@ static void _rumbleReadPins(struct GBACartridgeHardware* hw);
 static void _lightReadPins(struct GBACartridgeHardware* hw);
 
 static uint16_t _gbpRead(struct GBAKeyCallback*);
-static bool _gbpSioLoad(struct GBASIODriver* driver);
 static uint16_t _gbpSioWriteRegister(struct GBASIODriver* driver, uint32_t address, uint16_t value);
 static int32_t _gbpSioProcessEvents(struct GBASIODriver* driver, int32_t cycles);
 
@@ -52,7 +51,6 @@ void GBAHardwareClear(struct GBACartridgeHardware* hw) {
 	hw->direction = GPIO_WRITE_ONLY;
 	hw->pinState = 0;
 	hw->direction = 0;
-	hw->gbpRunning = false;
 }
 
 void GBAHardwareGPIOWrite(struct GBACartridgeHardware* hw, uint32_t address, uint16_t value) {
@@ -501,7 +499,7 @@ bool GBAHardwarePlayerCheckScreen(const struct GBAVideo* video) {
 }
 
 void GBAHardwarePlayerUpdate(struct GBA* gba) {
-	if (gba->memory.hw.gbpRunning) {
+	if (gba->memory.hw.devices & HW_GB_PLAYER) {
 		if (GBAHardwarePlayerCheckScreen(&gba->video)) {
 			++gba->memory.hw.gbpInputsPosted;
 			gba->memory.hw.gbpInputsPosted %= 3;
@@ -517,17 +515,18 @@ void GBAHardwarePlayerUpdate(struct GBA* gba) {
 		return;
 	}
 	if (GBAHardwarePlayerCheckScreen(&gba->video)) {
-		gba->memory.hw.gbpRunning = true;
+		gba->memory.hw.devices |= HW_GB_PLAYER;
 		gba->memory.hw.gbpCallback.d.readKeys = _gbpRead;
 		gba->memory.hw.gbpCallback.p = &gba->memory.hw;
 		gba->memory.hw.gbpDriver.d.init = 0;
 		gba->memory.hw.gbpDriver.d.deinit = 0;
-		gba->memory.hw.gbpDriver.d.load = _gbpSioLoad;
+		gba->memory.hw.gbpDriver.d.load = 0;
 		gba->memory.hw.gbpDriver.d.unload = 0;
 		gba->memory.hw.gbpDriver.d.writeRegister = _gbpSioWriteRegister;
 		gba->memory.hw.gbpDriver.d.processEvents = _gbpSioProcessEvents;
 		gba->memory.hw.gbpDriver.p = &gba->memory.hw;
 		gba->memory.hw.gbpInputsPosted = 0;
+		gba->memory.hw.gbpNextEvent = INT_MAX;
 		gba->keyCallback = &gba->memory.hw.gbpCallback.d;
 		GBASIOSetDriver(&gba->sio, &gba->memory.hw.gbpDriver.d, SIO_NORMAL_32);
 	}
@@ -541,13 +540,6 @@ uint16_t _gbpRead(struct GBAKeyCallback* callback) {
 	return 0x3FF;
 }
 
-bool _gbpSioLoad(struct GBASIODriver* driver) {
-	struct GBAGBPSIODriver* gbp = (struct GBAGBPSIODriver*) driver;
-	gbp->p->gbpTxPosition = 0;
-	gbp->p->gbpNextEvent = INT_MAX;
-	return true;
-}
-
 uint16_t _gbpSioWriteRegister(struct GBASIODriver* driver, uint32_t address, uint16_t value) {
 	struct GBAGBPSIODriver* gbp = (struct GBAGBPSIODriver*) driver;
 	if (address == REG_SIOCNT) {
@@ -608,6 +600,9 @@ void GBAHardwareSerialize(const struct GBACartridgeHardware* hw, struct GBASeria
 	state->hw.lightCounter = hw->lightCounter;
 	state->hw.lightSample = hw->lightSample;
 	state->hw.lightEdge = hw->lightEdge;
+	state->hw.gbpInputsPosted = hw->gbpInputsPosted;
+	state->hw.gbpTxPosition = hw->gbpTxPosition;
+	state->hw.gbpNextEvent = hw->gbpNextEvent;
 }
 
 void GBAHardwareDeserialize(struct GBACartridgeHardware* hw, const struct GBASerializedState* state) {
@@ -623,4 +618,7 @@ void GBAHardwareDeserialize(struct GBACartridgeHardware* hw, const struct GBASer
 	hw->lightCounter = state->hw.lightCounter;
 	hw->lightSample = state->hw.lightSample;
 	hw->lightEdge = state->hw.lightEdge;
+	hw->gbpInputsPosted = state->hw.gbpInputsPosted;
+	hw->gbpTxPosition = state->hw.gbpTxPosition;
+	hw->gbpNextEvent = state->hw.gbpNextEvent;
 }
diff --git a/src/gba/hardware.h b/src/gba/hardware.h
index 8a1930685..53a4899a7 100644
--- a/src/gba/hardware.h
+++ b/src/gba/hardware.h
@@ -33,7 +33,8 @@ enum GBAHardwareDevice {
 	HW_RUMBLE = 2,
 	HW_LIGHT_SENSOR = 4,
 	HW_GYRO = 8,
-	HW_TILT = 16
+	HW_TILT = 16,
+	HW_GB_PLAYER = 32
 };
 
 enum GPIORegister {
@@ -116,12 +117,11 @@ struct GBACartridgeHardware {
 	uint16_t tiltY;
 	int tiltState;
 
-	bool gbpRunning;
-	int gbpInputsPosted;
+	unsigned gbpInputsPosted;
 	int gbpTxPosition;
+	int32_t gbpNextEvent;
 	struct GBAGBPKeyCallback gbpCallback;
 	struct GBAGBPSIODriver gbpDriver;
-	int32_t gbpNextEvent;
 };
 
 void GBAHardwareInit(struct GBACartridgeHardware* gpio, uint16_t* gpioBase);
diff --git a/src/gba/serialize.h b/src/gba/serialize.h
index 1ccfd123c..4c23f4bb7 100644
--- a/src/gba/serialize.h
+++ b/src/gba/serialize.h
@@ -136,7 +136,8 @@ extern const uint32_t GBA_SAVESTATE_MAGIC;
  *   | bit 2: Has light sensor value
  *   | bit 3: Has gyroscope value
  *   | bit 4: Has tilt values
- *   | bits 5 - 7: Reserved
+ *   | bit 5: Has Game Boy Player attached
+ *   | bits 6 - 7: Reserved
  * | 0x002B8 - 0x002B9: Gyroscope sample
  * | 0x002BA - 0x002BB: Tilt x sample
  * | 0x002BC - 0x002BD: Tilt y sample
@@ -149,8 +150,11 @@ extern const uint32_t GBA_SAVESTATE_MAGIC;
  * | 0x002C0 - 0x002C0: Light sample
  * | 0x002C1 - 0x002C3: Flags
  *   | bits 0 - 1: Tilt state machine
- *   | bits 2 - 31: Reserved
- * 0x002C4 - 0x002DF: Reserved (leave zero)
+ *   | bits 2 - 3: GB Player inputs posted
+ *   | bits 4 - 8: GB Player transmit position
+ *   | bits 9 - 23: Reserved
+ * 0x002C4 - 0x002C7: Game Boy Player next event
+ * 0x002C8 - 0x002DF: Reserved (leave zero)
  * 0x002E0 - 0x002EF: Savedata state
  * | 0x002E0 - 0x002E0: Savedata type
  * | 0x002E1 - 0x002E1: Savedata command (see savedata.h)
@@ -282,10 +286,13 @@ struct GBASerializedState {
 		unsigned lightCounter : 12;
 		unsigned lightSample : 8;
 		unsigned tiltState : 2;
-		unsigned : 22;
+		unsigned gbpInputsPosted : 2;
+		unsigned gbpTxPosition : 5;
+		unsigned : 15;
+		uint32_t gbpNextEvent : 32;
 	} hw;
 
-	uint32_t reservedHardware[7];
+	uint32_t reservedHardware[6];
 
 	struct {
 		unsigned type : 8;