diff --git a/libethereum/BlockChain.cpp b/libethereum/BlockChain.cpp
index d29a8c6d8..d28474a9d 100644
--- a/libethereum/BlockChain.cpp
+++ b/libethereum/BlockChain.cpp
@@ -158,7 +158,7 @@ void BlockChain::import(bytes const& _block, Overlay const& _db)
 	// Check block doesn't already exist first!
 	if (details(newHash))
 	{
-		clog(BlockChainChat) << newHash << ": Not new.";
+		clog(BlockChainNote) << newHash << ": Not new.";
 		throw AlreadyHaveBlock();
 	}
 
@@ -166,11 +166,19 @@ void BlockChain::import(bytes const& _block, Overlay const& _db)
 	auto pd = details(bi.parentHash);
 	if (!pd)
 	{
-		clog(BlockChainChat) << newHash << ": Unknown parent " << bi.parentHash;
+		clog(BlockChainNote) << newHash << ": Unknown parent " << bi.parentHash;
 		// We don't know the parent (yet) - discard for now. It'll get resent to us if we find out about its ancestry later on.
 		throw UnknownParent();
 	}
 
+	// Check it's not crazy
+	if (bi.timestamp > (u256)time(0))
+	{
+		clog(BlockChainNote) << newHash << ": Future time " << bi.timestamp << " (now at " << time(0) << ")";
+		// We don't know the parent (yet) - discard for now. It'll get resent to us if we find out about its ancestry later on.
+		throw FutureTime();
+	}
+
 	clog(BlockChainNote) << "Attempting import of " << newHash << "...";
 
 	u256 td;
diff --git a/libethereum/BlockChain.h b/libethereum/BlockChain.h
index b295253c7..4c1500b06 100644
--- a/libethereum/BlockChain.h
+++ b/libethereum/BlockChain.h
@@ -58,6 +58,7 @@ class Overlay;
 
 class AlreadyHaveBlock: public std::exception {};
 class UnknownParent: public std::exception {};
+class FutureTime: public std::exception {};
 
 struct BlockChainChat: public LogChannel { static const char* name() { return "-B-"; } static const int verbosity = 7; };
 struct BlockChainNote: public LogChannel { static const char* name() { return "=B="; } static const int verbosity = 4; };