diff --git a/net/key/af_key.c b/net/key/af_key.c
index f0879c19f45259..a50d979b592660 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -365,6 +365,7 @@ static const u8 sadb_ext_min_len[] = {
 	[SADB_X_EXT_NAT_T_OA]		= (u8) sizeof(struct sadb_address),
 	[SADB_X_EXT_SEC_CTX]		= (u8) sizeof(struct sadb_x_sec_ctx),
 	[SADB_X_EXT_KMADDRESS]		= (u8) sizeof(struct sadb_x_kmaddress),
+	[SADB_X_EXT_FILTER]		= (u8) sizeof(struct sadb_x_filter),
 };
 
 /* Verify sadb_address_{len,prefixlen} against sa_family.  */