diff --git a/block/qcow.c b/block/qcow.c
index 041af26..a87bd69 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -725,8 +725,8 @@
     BlockDriverState *qcow_bs;
 
     /* Read out options */
-    total_size = DIV_ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
-                              BDRV_SECTOR_SIZE);
+    total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
+                          BDRV_SECTOR_SIZE);
     backing_file = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
     if (qemu_opt_get_bool_del(opts, BLOCK_OPT_ENCRYPT, false)) {
         flags |= BLOCK_FLAG_ENCRYPT;
@@ -754,7 +754,7 @@
     memset(&header, 0, sizeof(header));
     header.magic = cpu_to_be32(QCOW_MAGIC);
     header.version = cpu_to_be32(QCOW_VERSION);
-    header.size = cpu_to_be64(total_size * 512);
+    header.size = cpu_to_be64(total_size);
     header_size = sizeof(header);
     backing_filename_len = 0;
     if (backing_file) {
@@ -776,7 +776,7 @@
     }
     header_size = (header_size + 7) & ~7;
     shift = header.cluster_bits + header.l2_bits;
-    l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift;
+    l1_size = (total_size + (1LL << shift) - 1) >> shift;
 
     header.l1_table_offset = cpu_to_be64(header_size);
     if (flags & BLOCK_FLAG_ENCRYPT) {