diff --git a/ofproto/bond.c b/ofproto/bond.c
index 759f6cb7ffe..da35796aa87 100644
--- a/ofproto/bond.c
+++ b/ofproto/bond.c
@@ -83,7 +83,7 @@ struct bond_slave {
     void *aux;                  /* Client-provided handle for this slave. */
 
     struct netdev *netdev;      /* Network device, owned by the client. */
-    unsigned int change_seq;    /* Tracks changes in 'netdev'. */
+    uint64_t change_seq;        /* Tracks changes in 'netdev'. */
     ofp_port_t  ofp_port;       /* Open flow port number */
     char *name;                 /* Name (a copy of netdev_get_name(netdev)). */