diff --git a/tools/ublimage.h b/tools/ublimage.h
index 93ec8ee..e440625 100644
--- a/tools/ublimage.h
+++ b/tools/ublimage.h
@@ -66,7 +66,7 @@
 #define UBL_IMAGE_SIZE              (0x00003800u)
 
 /* one NAND block */
-#define UBL_BLOCK_SIZE 512
+#define UBL_BLOCK_SIZE 2048
 
 /* from sprufg5a.pdf Table 109 */
 struct ubl_header {