diff --git a/lib/bootstrap/disk.c b/lib/bootstrap/disk.c
index a55d5d7..fd01616 100644
--- a/lib/bootstrap/disk.c
+++ b/lib/bootstrap/disk.c
@@ -18,7 +18,7 @@
 {
 	int ret;
 	void *buf;
-	int len;
+	size_t len;
 	const char *path = "/";
 
 	ret = mount(dev, fstype, path, NULL);