--- xen-4.0.1/tools/blktap/drivers/bswap.h
+++ xen-4.0.1.mod/tools/blktap/drivers/bswap.h
@@ -15,6 +15,8 @@
 #define bswap_64(x) swap64(x)
 #else
 
+#define HAVE_BYTESWAP_H
+
 #ifdef HAVE_BYTESWAP_H
 #include <byteswap.h>
 #else