diff --git a/ports/esp32/modules/flashbdev.py b/ports/esp32/modules/flashbdev.py
index c3f75c7a7e..1ee6ff779b 100644
--- a/ports/esp32/modules/flashbdev.py
+++ b/ports/esp32/modules/flashbdev.py
@@ -3,5 +3,5 @@ from esp32 import Partition
 # MicroPython's partition table uses "vfs", TinyUF2 uses "ffat".
 bdev = Partition.find(Partition.TYPE_DATA, label="vfs")
 if not bdev:
-    bdev = Partition.find(Partition.TYPE_DATA, label="ffat")
+    bdev = Partition.find(Partition.TYPE_DATA, label="ffat", block_size=512)
 bdev = bdev[0] if bdev else None