diff --git a/src/gb/gb.c b/src/gb/gb.c
index 19331e1a6..137e81ac0 100644
--- a/src/gb/gb.c
+++ b/src/gb/gb.c
@@ -133,7 +133,7 @@ void GBResizeSram(struct GB* gb, size_t size) {
 				if (size & 0xFF) {
 					memcpy(&gb->memory.sram[gb->sramSize - (size & 0xFF)], extdataBuffer, size & 0xFF);
 				}
-			} else {
+			} else if (size > gb->sramSize || !gb->memory.sram) {
 				if (gb->memory.sram) {
 					vf->unmap(vf, gb->memory.sram, gb->sramSize);
 				}
@@ -145,6 +145,9 @@ void GBResizeSram(struct GB* gb, size_t size) {
 			}
 			gb->memory.sram = vf->map(vf, size, MAP_READ);
 		}
+		if (gb->memory.sram == (void*) -1) {
+			gb->memory.sram = NULL;
+		}
 	} else {
 		uint8_t* newSram = anonymousMemoryMap(size);
 		if (gb->memory.sram) {
@@ -160,7 +163,9 @@ void GBResizeSram(struct GB* gb, size_t size) {
 		}
 		gb->memory.sram = newSram;
 	}
-	gb->sramSize = size;
+	if (gb->sramSize < size) {
+		gb->sramSize = size;
+	}
 }
 
 void GBSavedataMask(struct GB* gb, struct VFile* vf) {
diff --git a/src/gb/mbc.c b/src/gb/mbc.c
index 88d0c5b0d..ece45db44 100644
--- a/src/gb/mbc.c
+++ b/src/gb/mbc.c
@@ -48,20 +48,34 @@ void GBMBCSwitchSramBank(struct GB* gb, int bank) {
 
 void GBMBCInit(struct GB* gb) {
 	const struct GBCartridge* cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
+	switch (cart->ramSize) {
+	case 0:
+		gb->sramSize = 0;
+		break;
+	case 1:
+		gb->sramSize = 0x800;
+		break;
+	default:
+	case 2:
+		gb->sramSize = 0x2000;
+		break;
+	case 3:
+		gb->sramSize = 0x8000;
+		break;
+	}
+
 	switch (cart->type) {
 	case 0:
 	case 8:
 	case 9:
 		gb->memory.mbc = _GBMBCNone;
 		gb->memory.mbcType = GB_MBC_NONE;
-		gb->sramSize = 0;
 		return;
 	case 1:
 	case 2:
 	case 3:
 		gb->memory.mbc = _GBMBC1;
 		gb->memory.mbcType = GB_MBC1;
-		gb->sramSize = 0x2000;
 		break;
 	case 5:
 	case 6:
@@ -76,7 +90,7 @@ void GBMBCInit(struct GB* gb) {
 	case 0x13:
 		gb->memory.mbc = _GBMBC3;
 		gb->memory.mbcType = GB_MBC3;
-		gb->sramSize = 0x2048;
+		gb->sramSize += 0x48;
 		break;
 	default:
 		mLOG(GB_MBC, WARN, "Unknown MBC type: %02X", cart->type);
@@ -86,14 +100,12 @@ void GBMBCInit(struct GB* gb) {
 	case 0x1B:
 		gb->memory.mbc = _GBMBC5;
 		gb->memory.mbcType = GB_MBC5;
-		gb->sramSize = 0x2000;
 		break;
 	case 0x1C:
 	case 0x1D:
 	case 0x1E:
 		gb->memory.mbc = _GBMBC5;
 		gb->memory.mbcType = GB_MBC5_RUMBLE;
-		gb->sramSize = 0x2000;
 		break;
 	case 0x20:
 		gb->memory.mbc = _GBMBC6;
@@ -108,7 +120,6 @@ void GBMBCInit(struct GB* gb) {
 	case 0xFE:
 		gb->memory.mbc = _GBHuC3;
 		gb->memory.mbcType = GB_HuC3;
-		gb->sramSize = 0x2000;
 		break;
 	}