diff --git a/src/blockchain_utilities/blockchain_stats.cpp b/src/blockchain_utilities/blockchain_stats.cpp
index 4cc84bf4a..33c26277e 100644
--- a/src/blockchain_utilities/blockchain_stats.cpp
+++ b/src/blockchain_utilities/blockchain_stats.cpp
@@ -205,7 +205,7 @@ plot 'stats.csv' index "DATA" using (timecolumn(1,"%Y-%m-%d")):4 with lines, ''
     char buf[8];
     unsigned int i;
     for (i=0; i<24; i++) {
-      sprintf(buf, "\t%02d:00", i);
+      sprintf(buf, "\t%02u:00", i);
       std::cout << buf;
     }
   }
diff --git a/src/cryptonote_basic/cryptonote_format_utils.cpp b/src/cryptonote_basic/cryptonote_format_utils.cpp
index fecd67729..566622c1a 100644
--- a/src/cryptonote_basic/cryptonote_format_utils.cpp
+++ b/src/cryptonote_basic/cryptonote_format_utils.cpp
@@ -1065,8 +1065,6 @@ namespace cryptonote
     // prefix
     get_transaction_prefix_hash(t, hashes[0]);
 
-    transaction &tt = const_cast<transaction&>(t);
-
     const blobdata blob = tx_to_blob(t);
     const unsigned int unprunable_size = t.unprunable_size;
     const unsigned int prefix_size = t.prefix_size;
diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index 08f077f07..8ab249ac1 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -3690,6 +3690,8 @@ leave:
         //TODO: why is this done?  make sure that keeping invalid blocks makes sense.
         add_block_as_invalid(bl, id);
         MERROR_VER("Block with id " << id << " added as invalid because of wrong inputs in transactions");
+        MERROR_VER("tx_index " << tx_index << ", m_blocks_txs_check " << m_blocks_txs_check.size() << ":");
+        for (const auto &h: m_blocks_txs_check) MERROR_VER("  " << h);
         bvc.m_verifivation_failed = true;
         return_tx_to_pool(txs);
         goto leave;