diff --git a/src/currency_core/currency_format_utils.cpp b/src/currency_core/currency_format_utils.cpp
index e9ef0eee..a2b05e2b 100644
--- a/src/currency_core/currency_format_utils.cpp
+++ b/src/currency_core/currency_format_utils.cpp
@@ -474,7 +474,7 @@ namespace currency
     }
 
     CHECK_AND_ASSERT_MES(destinations.size() <= CURRENCY_TX_MAX_ALLOWED_OUTS || height == 0, false, "Too many outs (" << destinations.size() << ")! Miner tx can't be constructed.");
-    tx = AUTO_VAL_INIT_T(transaction);
+    // tx is not cleared intentionally to allow passing additional args in the extra/attachments
     tx.version = tx_version;
 
     tx_generation_context tx_gen_context{};
diff --git a/tests/core_tests/pos_block_builder.cpp b/tests/core_tests/pos_block_builder.cpp
index 8d394d0e..62561121 100644
--- a/tests/core_tests/pos_block_builder.cpp
+++ b/tests/core_tests/pos_block_builder.cpp
@@ -169,6 +169,7 @@ void pos_block_builder::step4_generate_coinbase_tx(size_t median_size,
   uint64_t block_reward_without_fee = 0;
   m_block_reward = 0;
   size_t estimated_block_size = m_txs_total_size;
+  m_block.miner_tx = transaction{};
   bool r = construct_miner_tx(m_height, median_size, already_generated_coins, estimated_block_size, m_total_fee,
     reward_receiver_address, stakeholder_address, m_block.miner_tx, block_reward_without_fee, m_block_reward, tx_version, extra_nonce, max_outs, true, pe, &m_miner_tx_tgc, tx_one_time_key_to_use);
   CHECK_AND_ASSERT_THROW_MES(r, "construct_miner_tx failed");
@@ -177,6 +178,7 @@ void pos_block_builder::step4_generate_coinbase_tx(size_t median_size,
   size_t cumulative_size = 0;
   for (size_t try_count = 0; try_count != 10; ++try_count)
   {
+    m_block.miner_tx = transaction{};
     r = construct_miner_tx(m_height, median_size, already_generated_coins, estimated_block_size, m_total_fee,
     reward_receiver_address, stakeholder_address, m_block.miner_tx, block_reward_without_fee, m_block_reward, tx_version, extra_nonce, max_outs, true, pe, &m_miner_tx_tgc, tx_one_time_key_to_use);
     CHECK_AND_ASSERT_THROW_MES(r, "construct_homemade_pos_miner_tx failed");