From e18da34468508f11f4d5f8438a0d5ed27bf086bf Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Thu, 1 Jul 2021 13:34:56 +0100
Subject: [PATCH] miner: Set coinbase expiry height to block height from NU5
 activation

---
 src/miner.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/miner.cpp b/src/miner.cpp
index 63e31031a..31dcf5279 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -293,8 +293,14 @@ CMutableTransaction CreateCoinbaseTransaction(const CChainParams& chainparams, C
         CMutableTransaction mtx = CreateNewContextualCMutableTransaction(chainparams.GetConsensus(), nHeight);
         mtx.vin.resize(1);
         mtx.vin[0].prevout.SetNull();
-        // Set to 0 so expiry height does not apply to coinbase txs
-        mtx.nExpiryHeight = 0;
+        if (chainparams.GetConsensus().NetworkUpgradeActive(nHeight, Consensus::UPGRADE_NU5)) {
+            // ZIP 203: From NU5 onwards, nExpiryHeight is set to the block height in
+            // coinbase transactions.
+            mtx.nExpiryHeight = nHeight;
+        } else {
+            // Set to 0 so expiry height does not apply to coinbase txs
+            mtx.nExpiryHeight = 0;
+        }
 
         // Add outputs and sign
         std::visit(