diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index 113b907da0f757af7be920cc9b3a1b1c769f5804..3ba8e7e739b58a96e66ca64d38bff758500df3e1 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -44,6 +44,8 @@ static DEFINE_MUTEX(zones_mutex);
 struct zones_ht_key {
        struct net *net;
        u16 zone;
+       /* Note : pad[] must be the last field. */
+       u8  pad[];
 };
 
 struct tcf_ct_flow_table {
@@ -60,7 +62,7 @@ struct tcf_ct_flow_table {
 static const struct rhashtable_params zones_params = {
        .head_offset = offsetof(struct tcf_ct_flow_table, node),
        .key_offset = offsetof(struct tcf_ct_flow_table, key),
-       .key_len = sizeof_field(struct tcf_ct_flow_table, key),
+       .key_len = offsetof(struct zones_ht_key, pad),
        .automatic_shrinking = true,
 };