diff --git a/libethereum/BlockChain.h b/libethereum/BlockChain.h
index e3fcf83c1..2d3abd922 100644
--- a/libethereum/BlockChain.h
+++ b/libethereum/BlockChain.h
@@ -81,7 +81,8 @@ using BlocksHash = std::unordered_map<h256, bytes>;
 using TransactionHashes = h256s;
 using UncleHashes = h256s;
 
-struct ImportRoute {
+struct ImportRoute
+{
 	h256s deadBlocks;
 	h256s liveBlocks;
 };
diff --git a/libethereum/Client.cpp b/libethereum/Client.cpp
index 7d967f669..ea144c307 100644
--- a/libethereum/Client.cpp
+++ b/libethereum/Client.cpp
@@ -480,7 +480,7 @@ void Client::appendFromNewPending(TransactionReceipt const& _receipt, h256Hash&
 	}
 }
 
-void Client::appendFromBlock(h256 const& _block, bool _polarity, h256Hash& io_changed)
+void Client::appendFromBlock(h256 const& _block, BlockPolarity _polarity, h256Hash& io_changed)
 {
 	// TODO: more precise check on whether the txs match.
 	auto d = m_bc.info(_block);
@@ -682,7 +682,7 @@ void Client::onDeadBlocks(h256s const& _blocks, h256Hash& io_changed)
 	}
 
 	for (auto const& h: _blocks)
-		appendFromBlock(h, false, io_changed);
+		appendFromBlock(h, BlockPolarity::Dead, io_changed);
 }
 
 void Client::onNewBlocks(h256s const& _blocks, h256Hash& io_changed)
@@ -702,7 +702,7 @@ void Client::onNewBlocks(h256s const& _blocks, h256Hash& io_changed)
 		h->noteNewBlocks();
 
 	for (auto const& h: _blocks)
-		appendFromBlock(h, true, io_changed);
+		appendFromBlock(h, BlockPolarity::Live, io_changed);
 }
 
 void Client::restartMining()
diff --git a/libethereum/Client.h b/libethereum/Client.h
index eb05983b2..e25e8e0e4 100644
--- a/libethereum/Client.h
+++ b/libethereum/Client.h
@@ -251,7 +251,7 @@ protected:
 
 	/// Collate the changed filters for the hash of the given block.
 	/// Insert any filters that are activated into @a o_changed.
-	void appendFromBlock(h256 const& _blockHash, bool _polarity, h256Hash& io_changed);
+	void appendFromBlock(h256 const& _blockHash, BlockPolarity _polarity, h256Hash& io_changed);
 
 	/// Record that the set of filters @a _filters have changed.
 	/// This doesn't actually make any callbacks, but incrememnts some counters in m_watches.
diff --git a/libethereum/ClientBase.cpp b/libethereum/ClientBase.cpp
index d5bc0dbb9..2b25599cb 100644
--- a/libethereum/ClientBase.cpp
+++ b/libethereum/ClientBase.cpp
@@ -217,7 +217,7 @@ LocalisedLogEntries ClientBase::logs(LogFilter const& _f) const
 				{
 					total += le.size();
 					for (unsigned j = 0; j < le.size(); ++j)
-						ret.insert(ret.begin(), LocalisedLogEntry(le[j], info, th, i, logIndex));
+						ret.insert(ret.begin(), LocalisedLogEntry(le[j], info, th, i, logIndex, BlockPolarity::Live));
 				}
 			}
 			
diff --git a/libevm/ExtVMFace.h b/libevm/ExtVMFace.h
index 24c55d816..2d65631e0 100644
--- a/libevm/ExtVMFace.h
+++ b/libevm/ExtVMFace.h
@@ -36,6 +36,13 @@ namespace dev
 namespace eth
 {
 
+enum class BlockPolarity
+{
+	Unknown,
+	Dead,
+	Live
+};
+
 struct LogEntry
 {
 	LogEntry() {}
@@ -76,7 +83,7 @@ struct LocalisedLogEntry: public LogEntry
 		h256 _th,
 		unsigned _ti,
 		unsigned _li,
-	    bool _polarity = true
+	    BlockPolarity _polarity = BlockPolarity::Unknown
 	): LogEntry(_le), blockHash(_bi.hash()), blockNumber((BlockNumber)_bi.number), transactionHash(_th), transactionIndex(_ti), logIndex(_li), mined(true), polarity(_polarity) {};
 
 	h256 blockHash = h256();
@@ -85,7 +92,7 @@ struct LocalisedLogEntry: public LogEntry
 	unsigned transactionIndex = 0;
 	unsigned logIndex = 0;
 	bool mined = false;
-	bool polarity = true;
+	BlockPolarity polarity = BlockPolarity::Unknown;
 	h256 special = h256();
 };
 
diff --git a/libweb3jsonrpc/WebThreeStubServerBase.cpp b/libweb3jsonrpc/WebThreeStubServerBase.cpp
index f88443ee5..5bdd98e87 100644
--- a/libweb3jsonrpc/WebThreeStubServerBase.cpp
+++ b/libweb3jsonrpc/WebThreeStubServerBase.cpp
@@ -169,8 +169,11 @@ static Json::Value toJson(dev::eth::LocalisedLogEntry const& _e)
 		res["data"] = toJS(_e.data);
 		res["address"] = toJS(_e.address);
 		res["topics"] = Json::Value(Json::arrayValue);
+		res["polarity"] = _e.polarity == BlockPolarity::Live ? true : false;
+
 		for (auto const& t: _e.topics)
 			res["topics"].append(toJS(t));
+
 		if (_e.mined)
 		{
 			res["type"] = "mined";