diff --git a/net/net.c b/net/net.c
index bd51037..db09676 100644
--- a/net/net.c
+++ b/net/net.c
@@ -56,6 +56,7 @@
 #include "net/filter.h"
 #include "qapi/string-output-visitor.h"
 #include "qapi/qobject-input-visitor.h"
+#include "standard-headers/linux/virtio_net.h"
 
 /* Net bridge is currently not supported for W32. */
 #if !defined(_WIN32)
@@ -550,6 +551,10 @@
         return;
     }
 
+    assert(len == sizeof(struct virtio_net_hdr_mrg_rxbuf) ||
+           len == sizeof(struct virtio_net_hdr) ||
+           len == sizeof(struct virtio_net_hdr_v1_hash));
+
     nc->vnet_hdr_len = len;
     nc->info->set_vnet_hdr_len(nc, len);
 }