diff --git a/libdevcore/RLP.cpp b/libdevcore/RLP.cpp
index 25e843c77..846664cfd 100644
--- a/libdevcore/RLP.cpp
+++ b/libdevcore/RLP.cpp
@@ -166,6 +166,9 @@ unsigned RLP::length() const
 	{
 		if ((int)m_data.size() <= n - c_rlpDataIndLenZero)
 			BOOST_THROW_EXCEPTION(BadRLP());
+		if ((int)m_data.size() > 1)
+			if (m_data[1] == 0)
+				BOOST_THROW_EXCEPTION(BadRLP());
 		for (int i = 0; i < n - c_rlpDataIndLenZero; ++i)
 			ret = (ret << 8) | m_data[i + 1];
 	}
@@ -175,6 +178,9 @@ unsigned RLP::length() const
 	{
 		if ((int)m_data.size() <= n - c_rlpListIndLenZero)
 			BOOST_THROW_EXCEPTION(BadRLP());
+		if ((int)m_data.size() > 1)
+			if (m_data[1] == 0)
+				BOOST_THROW_EXCEPTION(BadRLP());
 		for (int i = 0; i < n - c_rlpListIndLenZero; ++i)
 			ret = (ret << 8) | m_data[i + 1];
 	}
diff --git a/libdevcore/RLP.h b/libdevcore/RLP.h
index c99d1a358..ac5e2ef1e 100644
--- a/libdevcore/RLP.h
+++ b/libdevcore/RLP.h
@@ -308,7 +308,7 @@ private:
 	/// Single-byte data payload.
 	bool isSingleByte() const { return !isNull() && m_data[0] < c_rlpDataImmLenStart; }
 
-	/// @returns the bytes used to encode the length of the data. Valid for all types.
+	/// @returns the amount of bytes used to encode the length of the data. Valid for all types.
 	unsigned lengthSize() const { if (isData() && m_data[0] > c_rlpDataIndLenZero) return m_data[0] - c_rlpDataIndLenZero; if (isList() && m_data[0] > c_rlpListIndLenZero) return m_data[0] - c_rlpListIndLenZero; return 0; }
 
 	/// @returns the size in bytes of the payload, as given by the RLP as opposed to as inferred from m_data.