diff --git a/src/gb/core.c b/src/gb/core.c
index 7f9d05c4e..c5569979b 100644
--- a/src/gb/core.c
+++ b/src/gb/core.c
@@ -644,8 +644,10 @@ static void _GBCoreReset(struct mCore* core) {
 	size_t i;
 	for (i = 0; i < sizeof(gbcore->memoryBlocks) / sizeof(*gbcore->memoryBlocks); ++i) {
 		if (gbcore->memoryBlocks[i].id == GB_REGION_CART_BANK0) {
+			gbcore->memoryBlocks[i].size = gb->memory.romSize;
 			gbcore->memoryBlocks[i].maxSegment = gb->memory.romSize / GB_SIZE_CART_BANK0;
 		} else if (gbcore->memoryBlocks[i].id == GB_REGION_EXTERNAL_RAM) {
+			gbcore->memoryBlocks[i].size = gb->sramSize;
 			gbcore->memoryBlocks[i].maxSegment = gb->sramSize / GB_SIZE_EXTERNAL_RAM;
 		} else {
 			continue;