diff --git a/CHANGES b/CHANGES
index 7e4d46688..08519a34c 100644
--- a/CHANGES
+++ b/CHANGES
@@ -7,6 +7,7 @@ Emulation fixes:
  - GB Timer: Fix timing adjustments when writing to TAC (fixes mgba.io/i/1340)
  - GBA Memory: Fix writing to OBJ memory in modes 3 and 5
  - GBA: Fix RTC on non-standard sized ROMs (fixes mgba.io/i/1400)
+ - GBA Memory: Prevent writing to mirrored BG VRAM (fixes mgba.io/i/743)
 Other fixes:
  - Qt: More app metadata fixes
  - Qt: Fix load recent from archive (fixes mgba.io/i/1325)
diff --git a/src/gba/memory.c b/src/gba/memory.c
index 72cf6e9a1..fddad0a20 100644
--- a/src/gba/memory.c
+++ b/src/gba/memory.c
@@ -390,11 +390,15 @@ static void GBASetActiveRegion(struct ARMCore* cpu, uint32_t address) {
 	wait += waitstatesRegion[REGION_PALETTE_RAM];
 
 #define LOAD_VRAM \
-	if ((address & 0x0001FFFF) < SIZE_VRAM) { \
-		LOAD_32(value, address & 0x0001FFFC, gba->video.vram); \
-	} else { \
-		LOAD_32(value, address & 0x00017FFC, gba->video.vram); \
+	if ((address & 0x0001FFFF) >= SIZE_VRAM) { \
+		if ((address & (SIZE_VRAM | 0x00014000)) == SIZE_VRAM && (GBARegisterDISPCNTGetMode(gba->memory.io[REG_DISPCNT >> 1]) >= 3)) { \
+			mLOG(GBA_MEM, GAME_ERROR, "Bad VRAM Load32: 0x%08X", address); \
+			value = 0; \
+			break; \
+		} \
+		address &= 0x00017FFC; \
 	} \
+	LOAD_32(value, address & 0x0001FFFC, gba->video.vram); \
 	wait += waitstatesRegion[REGION_VRAM];
 
 #define LOAD_OAM LOAD_32(value, address & (SIZE_OAM - 4), gba->video.oam.raw);
@@ -520,11 +524,15 @@ uint32_t GBALoad16(struct ARMCore* cpu, uint32_t address, int* cycleCounter) {
 		LOAD_16(value, address & (SIZE_PALETTE_RAM - 2), gba->video.palette);
 		break;
 	case REGION_VRAM:
-		if ((address & 0x0001FFFF) < SIZE_VRAM) {
-			LOAD_16(value, address & 0x0001FFFE, gba->video.vram);
-		} else {
-			LOAD_16(value, address & 0x00017FFE, gba->video.vram);
+		if ((address & 0x0001FFFF) >= SIZE_VRAM) {
+			if ((address & (SIZE_VRAM | 0x00014000)) == SIZE_VRAM && (GBARegisterDISPCNTGetMode(gba->memory.io[REG_DISPCNT >> 1]) >= 3)) {
+				mLOG(GBA_MEM, GAME_ERROR, "Bad VRAM Load16: 0x%08X", address);
+				value = 0;
+				break;
+			}
+			address &= 0x00017FFE;
 		}
+		LOAD_16(value, address & 0x0001FFFE, gba->video.vram);
 		break;
 	case REGION_OAM:
 		LOAD_16(value, address & (SIZE_OAM - 2), gba->video.oam.raw);
@@ -631,11 +639,15 @@ uint32_t GBALoad8(struct ARMCore* cpu, uint32_t address, int* cycleCounter) {
 		value = ((uint8_t*) gba->video.palette)[address & (SIZE_PALETTE_RAM - 1)];
 		break;
 	case REGION_VRAM:
-		if ((address & 0x0001FFFF) < SIZE_VRAM) {
-			value = ((uint8_t*) gba->video.vram)[address & 0x0001FFFF];
-		} else {
-			value = ((uint8_t*) gba->video.vram)[address & 0x00017FFF];
+		if ((address & 0x0001FFFF) >= SIZE_VRAM) {
+			if ((address & (SIZE_VRAM | 0x00014000)) == SIZE_VRAM && (GBARegisterDISPCNTGetMode(gba->memory.io[REG_DISPCNT >> 1]) >= 3)) {
+				mLOG(GBA_MEM, GAME_ERROR, "Bad VRAM Load8: 0x%08X", address);
+				value = 0;
+				break;
+			}
+			address &= 0x00017FFF;
 		}
+		value = ((uint8_t*) gba->video.vram)[address & 0x0001FFFF];
 		break;
 	case REGION_OAM:
 		value = ((uint8_t*) gba->video.oam.raw)[address & (SIZE_OAM - 1)];
@@ -717,20 +729,18 @@ uint32_t GBALoad8(struct ARMCore* cpu, uint32_t address, int* cycleCounter) {
 	wait += waitstatesRegion[REGION_PALETTE_RAM];
 
 #define STORE_VRAM \
-	if ((address & 0x0001FFFF) < SIZE_VRAM) { \
-		LOAD_32(oldValue, address & 0x0001FFFC, gba->video.vram); \
-		if (oldValue != value) { \
-			STORE_32(value, address & 0x0001FFFC, gba->video.vram); \
-			gba->video.renderer->writeVRAM(gba->video.renderer, (address & 0x0001FFFC) + 2); \
-			gba->video.renderer->writeVRAM(gba->video.renderer, (address & 0x0001FFFC)); \
-		} \
-	} else { \
-		LOAD_32(oldValue, address & 0x00017FFC, gba->video.vram); \
-		if (oldValue != value) { \
-			STORE_32(value, address & 0x00017FFC, gba->video.vram); \
-			gba->video.renderer->writeVRAM(gba->video.renderer, (address & 0x00017FFC) + 2); \
-			gba->video.renderer->writeVRAM(gba->video.renderer, (address & 0x00017FFC)); \
+	if ((address & 0x0001FFFF) >= SIZE_VRAM) { \
+		if ((address & (SIZE_VRAM | 0x00014000)) == SIZE_VRAM && (GBARegisterDISPCNTGetMode(gba->memory.io[REG_DISPCNT >> 1]) >= 3)) { \
+			mLOG(GBA_MEM, GAME_ERROR, "Bad VRAM Store32: 0x%08X", address); \
+			break; \
 		} \
+		address &= 0x00017FFC; \
+	} \
+	LOAD_32(oldValue, address & 0x0001FFFC, gba->video.vram); \
+	if (oldValue != value) { \
+		STORE_32(value, address & 0x0001FFFC, gba->video.vram); \
+		gba->video.renderer->writeVRAM(gba->video.renderer, (address & 0x0001FFFC) + 2); \
+		gba->video.renderer->writeVRAM(gba->video.renderer, (address & 0x0001FFFC)); \
 	} \
 	wait += waitstatesRegion[REGION_VRAM];
 
@@ -840,18 +850,17 @@ void GBAStore16(struct ARMCore* cpu, uint32_t address, int16_t value, int* cycle
 		}
 		break;
 	case REGION_VRAM:
-		if ((address & 0x0001FFFF) < SIZE_VRAM) {
-			LOAD_16(oldValue, address & 0x0001FFFE, gba->video.vram);
-			if (value != oldValue) {
-				STORE_16(value, address & 0x0001FFFE, gba->video.vram);
-				gba->video.renderer->writeVRAM(gba->video.renderer, address & 0x0001FFFE);
-			}
-		} else {
-			LOAD_16(oldValue, address & 0x00017FFE, gba->video.vram);
-			if (value != oldValue) {
-				STORE_16(value, address & 0x00017FFE, gba->video.vram);
-				gba->video.renderer->writeVRAM(gba->video.renderer, address & 0x00017FFE);
+		if ((address & 0x0001FFFF) >= SIZE_VRAM) {
+			if ((address & (SIZE_VRAM | 0x00014000)) == SIZE_VRAM && (GBARegisterDISPCNTGetMode(gba->memory.io[REG_DISPCNT >> 1]) >= 3)) {
+				mLOG(GBA_MEM, GAME_ERROR, "Bad VRAM Store16: 0x%08X", address);
+				break;
 			}
+			address &= 0x00017FFE;
+		}
+		LOAD_16(oldValue, address & 0x0001FFFE, gba->video.vram);
+		if (value != oldValue) {
+			STORE_16(value, address & 0x0001FFFE, gba->video.vram);
+			gba->video.renderer->writeVRAM(gba->video.renderer, address & 0x0001FFFE);
 		}
 		break;
 	case REGION_OAM:
@@ -939,7 +948,6 @@ void GBAStore8(struct ARMCore* cpu, uint32_t address, int8_t value, int* cycleCo
 		break;
 	case REGION_VRAM:
 		if ((address & 0x0001FFFF) >= ((GBARegisterDISPCNTGetMode(gba->memory.io[REG_DISPCNT >> 1]) >= 3) ? 0x00014000 : 0x00010000)) {
-			// TODO: check BG mode
 			mLOG(GBA_MEM, GAME_ERROR, "Cannot Store8 to OBJ: 0x%08X", address);
 			break;
 		}