diff --git a/include/bbu.h b/include/bbu.h
index a3824e1..def568e 100644
--- a/include/bbu.h
+++ b/include/bbu.h
@@ -11,7 +11,7 @@
 #define BBU_FLAG_YES	(1 << 1)
 	unsigned long flags;
 	int force;
-	void *image;
+	const void *image;
 	const char *imagefile;
 	const char *devicefile;
 	size_t len;