diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_fs_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_fs_ethtool.c
index bdd82c9b3992..22fb993987b4 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_fs_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_fs_ethtool.c
@@ -276,7 +276,7 @@ static void add_rule_to_list(struct mlx5e_priv *priv,
 
 static bool outer_header_zero(u32 *match_criteria)
 {
-	int size = MLX5_ST_SZ_BYTES(fte_match_param);
+	int size = MLX5_FLD_SZ_BYTES(fte_match_param, outer_headers);
 	char *outer_headers_c = MLX5_ADDR_OF(fte_match_param, match_criteria,
 					     outer_headers);