diff --git a/src/libcharon/sa/ikev2/keymat_v2.c b/src/libcharon/sa/ikev2/keymat_v2.c
index 6fedc8eb5..b57306b66 100644
--- a/src/libcharon/sa/ikev2/keymat_v2.c
+++ b/src/libcharon/sa/ikev2/keymat_v2.c
@@ -112,6 +112,7 @@ static bool derive_ike_aead(private_keymat_v2_t *this, u_int16_t alg,
 		case ENCR_AES_GCM_ICV12:
 		case ENCR_AES_GCM_ICV16:
 			/* RFC 4106 */
+		case ENCR_CHACHA20_POLY1305:
 			salt_size = 4;
 			break;
 		case ENCR_AES_CCM_ICV8: