diff --git a/crypto/block-qcow.c b/crypto/block-qcow.c
index a456fe3..4dd594a 100644
--- a/crypto/block-qcow.c
+++ b/crypto/block-qcow.c
@@ -80,6 +80,7 @@
         goto fail;
     }
 
+    block->sector_size = QCRYPTO_BLOCK_QCOW_SECTOR_SIZE;
     block->payload_offset = 0;
 
     return 0;