diff --git a/include/mgba/internal/gba/cart/unlicensed.h b/include/mgba/internal/gba/cart/unlicensed.h
index 816aa1dfd..f9adbee7e 100644
--- a/include/mgba/internal/gba/cart/unlicensed.h
+++ b/include/mgba/internal/gba/cart/unlicensed.h
@@ -42,6 +42,7 @@ struct GBAMulticart {
 	uint8_t offset;
 	uint8_t size;
 	bool sramActive;
+	bool locked;
 	uint8_t unk;
 };
 
diff --git a/include/mgba/internal/gba/serialize.h b/include/mgba/internal/gba/serialize.h
index eda589dfd..6e9a3124a 100644
--- a/include/mgba/internal/gba/serialize.h
+++ b/include/mgba/internal/gba/serialize.h
@@ -295,6 +295,7 @@ DECL_BITS(GBASerializedUnlCartFlags, Subtype, 5, 3);
 
 DECL_BITFIELD(GBASerializedMulticartFlags, uint32_t);
 DECL_BIT(GBASerializedMulticartFlags, DustSettling, 0);
+DECL_BIT(GBASerializedMulticartFlags, Locked, 1);
 
 DECL_BITFIELD(GBASerializedSavedataFlags, uint8_t);
 DECL_BITS(GBASerializedSavedataFlags, FlashState, 0, 2);
diff --git a/src/gba/cart/unlicensed.c b/src/gba/cart/unlicensed.c
index ed3b9ce3a..a286850e5 100644
--- a/src/gba/cart/unlicensed.c
+++ b/src/gba/cart/unlicensed.c
@@ -69,6 +69,7 @@ void GBAUnlCartReset(struct GBA* gba) {
 		gba->memory.unl.multi.bank = 0;
 		gba->memory.unl.multi.offset = 0;
 		gba->memory.unl.multi.size = 0;
+		gba->memory.unl.multi.locked = false;
 		gba->memory.rom = gba->memory.unl.multi.rom;
 		gba->memory.romSize = GBA_SIZE_ROM0;
 	}
@@ -93,22 +94,25 @@ void GBAUnlCartWriteSRAM(struct GBA* gba, uint32_t address, uint8_t value) {
 		mLOG(GBA_MEM, DEBUG, "Multicart writing SRAM %06X:%02X", address, value);
 		switch (address) {
 		case GBA_MULTICART_CFG_BANK:
-			unl->multi.bank = value >> 4;
-			if (!(unl->multi.offset & 0x80)) {
+			if (!unl->multi.locked) {
+				unl->multi.bank = value >> 4;
 				mTimingDeschedule(&gba->timing, &unl->multi.settle);
 				mTimingSchedule(&gba->timing, &unl->multi.settle, MULTI_SETTLE);
 			}
 			break;
 		case GBA_MULTICART_CFG_OFFSET:
-			unl->multi.offset = value;
-			if (!(unl->multi.offset & 0x80)) {
+			if (!unl->multi.locked) {
+				unl->multi.offset = value;
 				mTimingDeschedule(&gba->timing, &unl->multi.settle);
 				mTimingSchedule(&gba->timing, &unl->multi.settle, MULTI_SETTLE);
+				if (unl->multi.offset & 0x80) {
+					unl->multi.locked = true;
+				}
 			}
 			break;
 		case GBA_MULTICART_CFG_SIZE:
 			unl->multi.size = 0x40 - (value & 0x3F);
-			if (!(unl->multi.offset & 0x80)) {
+			if (!unl->multi.locked) {
 				mTimingDeschedule(&gba->timing, &unl->multi.settle);
 				mTimingSchedule(&gba->timing, &unl->multi.settle, MULTI_SETTLE);
 			}
@@ -167,6 +171,7 @@ static void _multicartSettle(struct mTiming* timing, void* context, uint32_t cyc
 
 void GBAUnlCartSerialize(const struct GBA* gba, struct GBASerializedState* state) {
 	GBASerializedUnlCartFlags flags = 0;
+	GBASerializedMulticartFlags multiFlags = 0;
 	const struct GBAUnlCart* unl = &gba->memory.unl;
 	switch (unl->type) {
 	case GBA_UNL_CART_NONE:
@@ -187,11 +192,13 @@ void GBAUnlCartSerialize(const struct GBA* gba, struct GBASerializedState* state
 		state->multicart.sramActive = unl->multi.sramActive;
 		state->multicart.unk = unl->multi.unk;
 		state->multicart.currentSize = gba->memory.romSize / MULTI_BLOCK;
+		multiFlags = GBASerializedMulticartFlagsSetLocked(flags, unl->multi.locked);
 		STORE_16((gba->memory.rom - unl->multi.rom) / 0x20000, 0, &state->multicart.currentOffset);
 		STORE_32(unl->multi.settle.when, 0, &state->multicart.settleNextEvent);
 		if (mTimingIsScheduled(&gba->timing, &unl->multi.settle)) {
-			STORE_32(GBASerializedMulticartFlagsFillDustSettling(0), 0, &state->multicart.flags);
+			multiFlags = GBASerializedMulticartFlagsFillDustSettling(multiFlags);
 		}
+		STORE_32(multiFlags, 0, &state->multicart.flags);
 		break;
 	}
 	STORE_32(flags, 0, &state->hw.unlCartFlags);
@@ -238,6 +245,7 @@ void GBAUnlCartDeserialize(struct GBA* gba, const struct GBASerializedState* sta
 			gba->memory.rom = unl->multi.rom + offset;
 		}
 		LOAD_32(multiFlags, 0, &state->multicart.flags);
+		unl->multi.locked = GBASerializedMulticartFlagsGetLocked(multiFlags);
 		if (GBASerializedMulticartFlagsIsDustSettling(multiFlags)) {
 			LOAD_32(when, 0, &state->multicart.settleNextEvent);
 			mTimingSchedule(&gba->timing, &unl->multi.settle, when);
diff --git a/src/gba/io.c b/src/gba/io.c
index a72171c1f..cb6058f7f 100644
--- a/src/gba/io.c
+++ b/src/gba/io.c
@@ -1033,7 +1033,6 @@ void GBAIOSerialize(struct GBA* gba, struct GBASerializedState* state) {
 	STORE_32(gba->bus, 0, &state->bus);
 
 	GBAHardwareSerialize(&gba->memory.hw, state);
-	GBAUnlCartSerialize(gba, state);
 }
 
 void GBAIODeserialize(struct GBA* gba, const struct GBASerializedState* state) {
@@ -1083,5 +1082,4 @@ void GBAIODeserialize(struct GBA* gba, const struct GBASerializedState* state) {
 	GBADMARecalculateCycles(gba);
 	GBADMAUpdate(gba);
 	GBAHardwareDeserialize(&gba->memory.hw, state);
-	GBAUnlCartDeserialize(gba, state);
 }
diff --git a/src/gba/serialize.c b/src/gba/serialize.c
index 9d6130385..3866c0c80 100644
--- a/src/gba/serialize.c
+++ b/src/gba/serialize.c
@@ -83,6 +83,7 @@ void GBASerialize(struct GBA* gba, struct GBASerializedState* state) {
 
 	GBAMemorySerialize(&gba->memory, state);
 	GBAIOSerialize(gba, state);
+	GBAUnlCartSerialize(gba, state);
 	GBAVideoSerialize(&gba->video, state);
 	GBAAudioSerialize(&gba->audio, state);
 	GBASavedataSerialize(&gba->memory.savedata, state);
@@ -180,6 +181,9 @@ bool GBADeserialize(struct GBA* gba, const struct GBASerializedState* state) {
 		mLOG(GBA_STATE, WARN, "Savestate has unaligned PC and is probably corrupted");
 		gba->cpu->gprs[ARM_PC] &= ~1;
 	}
+
+	// Since this can remap the ROM, we need to do this before we reset the pipeline
+	GBAUnlCartDeserialize(gba, state);
 	gba->memory.activeRegion = -1;
 	gba->cpu->memory.setActiveRegion(gba->cpu, gba->cpu->gprs[ARM_PC]);
 	if (state->biosPrefetch) {