diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 196a46e7467d..ce0de02f5a3a 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -612,6 +612,7 @@ static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
 		ext->data_seq = data_fin_tx_seq;
 		ext->subflow_seq = 0;
 		ext->data_len = 1;
+		ext->csum = 0;
 	} else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
 		/* If there's an existing DSS mapping and it is the
 		 * final mapping, DATA_FIN consumes 1 additional byte of