diff --git a/block.h b/block.h
index db131a3438da85e38c06a7b8f0f74cd25ea39ad3..5f6438010f84c925cbf18f277cd91870f42c78b5 100644
--- a/block.h
+++ b/block.h
@@ -35,7 +35,7 @@ typedef struct QEMUSnapshotInfo {
 #define BDRV_O_NO_BACKING  0x0100 /* don't open the backing file */
 #define BDRV_O_NO_FLUSH    0x0200 /* disable flushing on this disk */
 
-#define BDRV_O_CACHE_MASK  (BDRV_O_NOCACHE | BDRV_O_CACHE_WB)
+#define BDRV_O_CACHE_MASK  (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)
 
 #define BDRV_SECTOR_BITS   9
 #define BDRV_SECTOR_SIZE   (1ULL << BDRV_SECTOR_BITS)