diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index fb2c71a3a..3803ef1f6 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -1106,7 +1106,7 @@ difficulty_type Blockchain::get_next_difficulty_for_alternative_chain(const std:
     size_t count = 0;
     size_t max_i = timestamps.size()-1;
     // get difficulties and timestamps from most recent blocks in alt chain
-    for (const auto bei: boost::adaptors::reverse(alt_chain))
+    for (const auto &bei: boost::adaptors::reverse(alt_chain))
     {
       timestamps[max_i - count] = bei.bl.timestamp;
       cumulative_difficulties[max_i - count] = bei.cumulative_difficulty;
diff --git a/src/device/device_ledger.cpp b/src/device/device_ledger.cpp
index 222a84d3f..6295d5310 100644
--- a/src/device/device_ledger.cpp
+++ b/src/device/device_ledger.cpp
@@ -1548,7 +1548,7 @@ namespace hw {
       const bool                               need_additional_txkeys_x       = need_additional_txkeys;
       
       std::vector<crypto::secret_key>    additional_tx_keys_x;
-      for (const auto k: additional_tx_keys) {
+      for (const auto &k: additional_tx_keys) {
         additional_tx_keys_x.push_back(hw::ledger::decrypt(k));
       }