diff --git a/DuetPkg/DuetPkg.fdf b/DuetPkg/DuetPkg.fdf
index 0e5bd9b1b9..a3d4c5c369 100644
--- a/DuetPkg/DuetPkg.fdf
+++ b/DuetPkg/DuetPkg.fdf
@@ -45,6 +45,7 @@ NumBlocks     = 0x2a
 #
 ################################################################################
 [FV.DuetEfiMainFv]
+BlockSize          = 0x100000
 FvAlignment        = 16         #FV alignment and FV attributes setting.
 ERASE_POLARITY     = 1
 MEMORY_MAPPED      = TRUE