diff --git a/src/quic_tx.c b/src/quic_tx.c
index e36bb2fdf..611788b15 100644
--- a/src/quic_tx.c
+++ b/src/quic_tx.c
@@ -1685,6 +1685,7 @@ static void qc_build_cc_frm(struct quic_conn *qc, struct quic_enc_level *qel,
 			 * converting to a CONNECTION_CLOSE of type 0x1c.
 			 */
 			out->type = QUIC_FT_CONNECTION_CLOSE;
+			out->connection_close.frame_type = 0;
 			out->connection_close.error_code = QC_ERR_APPLICATION_ERROR;
 			out->connection_close.reason_phrase_len = 0;
 		}
@@ -1696,6 +1697,7 @@ static void qc_build_cc_frm(struct quic_conn *qc, struct quic_enc_level *qel,
 	}
 	else {
 		out->type = QUIC_FT_CONNECTION_CLOSE;
+		out->connection_close.frame_type = 0;
 		out->connection_close.error_code = qc->err.code;
 		out->connection_close.reason_phrase_len = 0;
 	}