diff --git a/bip-0370.mediawiki b/bip-0370.mediawiki
index 0adb6af3..93b56e88 100644
--- a/bip-0370.mediawiki
+++ b/bip-0370.mediawiki
@@ -278,6 +278,11 @@ If the Signer added a signature that does not use SIGHASH_ANYONECANPAY, the Inpu
 If the Signer added a signature that does not use SIGHASH_NONE, the Outputs Modifiable flag must be set to False.
 If the Signer added a signature that uses SIGHASH_SINGLE, the Has SIGHASH_SINGLE flag must be set to True.
 
+===Input Finalizer===
+
+For PSBTv2s, when the Input Finalizer clears a finalized input's fields as BIP 174 asks, it must keep PSBT_IN_PREVIOUS_TXID, PSBT_IN_OUTPUT_INDEX, PSBT_IN_SEQUENCE, PSBT_IN_REQUIRED_TIME_LOCKTIME and PSBT_IN_REQUIRED_HEIGHT_LOCKTIME.
+The Transaction Extractor constructs the transaction from these fields, and an input missing either PSBT_IN_PREVIOUS_TXID or PSBT_IN_OUTPUT_INDEX is invalid.
+
 ===Transaction Extractor===
 
 For PSBTv2s, the transaction is constructed using the PSBTv2 fields.