diff --git a/CHANGES b/CHANGES
index 3e3577907..f624e78ce 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5,6 +5,7 @@ Bugfixes:
  - GB Video: Only trigger STAT write IRQs when screen is on (fixes mgba.io/i/912)
  - GBA Cheats: Fix PARv3 slide codes (fixes mgba.io/i/919)
  - GBA Video: OBJWIN can change blend params after OBJ is drawn (fixes mgba.io/i/921)
+ - GBA Savedata: Fix crash when resizing flash
 Misc:
  - GBA: Improve multiboot image detection
 
diff --git a/src/gba/savedata.c b/src/gba/savedata.c
index 3008b9428..c8c6c8be7 100644
--- a/src/gba/savedata.c
+++ b/src/gba/savedata.c
@@ -576,9 +576,15 @@ void _flashSwitchBank(struct GBASavedata* savedata, int bank) {
 	if (bank > 0 && savedata->type == SAVEDATA_FLASH512) {
 		mLOG(GBA_SAVE, INFO, "Updating flash chip from 512kb to 1Mb");
 		savedata->type = SAVEDATA_FLASH1M;
-		if (savedata->vf && savedata->vf->size(savedata->vf) == SIZE_CART_FLASH512) {
-			savedata->vf->truncate(savedata->vf, SIZE_CART_FLASH1M);
-			memset(&savedata->data[SIZE_CART_FLASH512], 0xFF, SIZE_CART_FLASH512);
+		if (savedata->vf) {
+			savedata->vf->unmap(savedata->vf, savedata->data, SIZE_CART_FLASH512);
+			if (savedata->vf->size(savedata->vf) == SIZE_CART_FLASH512) {
+				savedata->vf->truncate(savedata->vf, SIZE_CART_FLASH1M);
+				savedata->data = savedata->vf->map(savedata->vf, SIZE_CART_FLASH1M, MAP_WRITE);
+				memset(&savedata->data[SIZE_CART_FLASH512], 0xFF, SIZE_CART_FLASH512);
+			} else {
+				savedata->data = savedata->vf->map(savedata->vf, SIZE_CART_FLASH1M, MAP_WRITE);
+			}
 		}
 	}
 }