diff --git a/vl.h b/vl.h
index a8a70af..4cfe9c0 100644
--- a/vl.h
+++ b/vl.h
@@ -354,6 +354,7 @@
 extern BlockDriver bdrv_cow;
 extern BlockDriver bdrv_qcow;
 extern BlockDriver bdrv_vmdk;
+extern BlockDriver bdrv_cloop;
 
 void bdrv_init(void);
 BlockDriver *bdrv_find_format(const char *format_name);