diff --git a/libethcore/Common.h b/libethcore/Common.h
index 25a6a8e1d..732d09981 100644
--- a/libethcore/Common.h
+++ b/libethcore/Common.h
@@ -112,6 +112,7 @@ enum class ImportResult
 	AlreadyInChain,
 	AlreadyKnown,
 	Malformed,
+	OverbidGasPrice,
 	BadChain
 };
 
diff --git a/libethereum/Client.cpp b/libethereum/Client.cpp
index ad551c2ec..2b0a64491 100644
--- a/libethereum/Client.cpp
+++ b/libethereum/Client.cpp
@@ -105,7 +105,8 @@ void Client::onBadBlock(Exception& _ex) const
 	bytes const* block = boost::get_error_info<errinfo_block>(_ex);
 	if (!block)
 	{
-		cwarn << "ODD: onBadBlock called but exception has no block in it.";
+		cwarn << "ODD: onBadBlock called but exception (" << _ex.what() << ") has no block in it.";
+		cwarn << boost::diagnostic_information(_ex, true);
 		return;
 	}
 
diff --git a/libethereum/TransactionQueue.cpp b/libethereum/TransactionQueue.cpp
index a86f6abf3..8931ee218 100644
--- a/libethereum/TransactionQueue.cpp
+++ b/libethereum/TransactionQueue.cpp
@@ -113,6 +113,26 @@ ImportResult TransactionQueue::manageImport_WITH_LOCK(h256 const& _h, Transactio
 		// If it doesn't work, the signature is bad.
 		// The transaction's nonce may yet be invalid (or, it could be "valid" but we may be missing a marginally older transaction).
 
+		auto r = m_senders.equal_range(_transaction.from());
+		for (auto it = r.first; it != r.second; ++it)
+			if (m_current.count(it->second) && m_current[it->second].nonce() == _transaction.nonce())
+				if (_transaction.gasPrice() < m_current[it->second].gasPrice())
+					return ImportResult::OverbidGasPrice;
+				else
+				{
+					remove_WITH_LOCK(it->second);
+					break;
+				}
+			else if (m_future.count(it->second) && m_future[it->second].nonce() == _transaction.nonce())
+				if (_transaction.gasPrice() < m_future[it->second].gasPrice())
+					return ImportResult::OverbidGasPrice;
+				else
+				{
+					remove_WITH_LOCK(it->second);
+					break;
+				}
+			else {}
+
 		// If valid, append to blocks.
 		insertCurrent_WITH_LOCK(make_pair(_h, _transaction));
 		m_known.insert(_h);