diff --git a/blk-virtio.c b/blk-virtio.c
index 13e6d90..3f79f81 100644
--- a/blk-virtio.c
+++ b/blk-virtio.c
@@ -270,7 +270,7 @@ void blk_virtio__init(struct kvm *self)
 	if (!self->disk_image)
 		return;
 
-	device.blk_config.capacity = self->disk_image->size / 512;
+	device.blk_config.capacity = self->disk_image->size / SECTOR_SIZE;
 
 	pci__register(&blk_virtio_pci_device, 1);
 
diff --git a/disk-image.c b/disk-image.c
index fd2d968..7aca1cc 100644
--- a/disk-image.c
+++ b/disk-image.c
@@ -12,9 +12,6 @@
 #include <unistd.h>
 #include <fcntl.h>
 
-#define SECTOR_SHIFT		9
-#define SECTOR_SIZE		(1UL << SECTOR_SHIFT)
-
 static const char QCOW_MAGIC[]	= { 'Q', 'F', 'I', 0xfb };
 
 struct qcow_header {
diff --git a/include/kvm/disk-image.h b/include/kvm/disk-image.h
index c6413ca..25b31d6 100644
--- a/include/kvm/disk-image.h
+++ b/include/kvm/disk-image.h
@@ -3,6 +3,9 @@
 
 #include <stdint.h>
 
+#define SECTOR_SHIFT		9
+#define SECTOR_SIZE		(1UL << SECTOR_SHIFT)
+
 struct disk_image {
 	void		*mmap;
 	int		fd;