diff --git a/libethcore/BlockInfo.h b/libethcore/BlockInfo.h
index 389d0a8ef..d37b70302 100644
--- a/libethcore/BlockInfo.h
+++ b/libethcore/BlockInfo.h
@@ -128,6 +128,7 @@ public:
 	void setCoinbaseAddress(Address const& _v) { m_coinbaseAddress = _v; noteDirty(); }
 	void setRoots(h256 const& _t, h256 const& _r, h256 const& _u, h256 const& _s) { m_transactionsRoot = _t; m_receiptsRoot = _r; m_stateRoot = _s; m_sha3Uncles = _u; noteDirty(); }
 	void setGasUsed(u256 const& _v) { m_gasUsed = _v; noteDirty(); }
+	void setNumber(u256 const& _v) { m_number = _v; noteDirty(); }
 	void setGasLimit(u256 const& _v) { m_gasLimit = _v; noteDirty(); }
 	void setExtraData(bytes const& _v) { m_extraData = _v; noteDirty(); }
 	void setLogBloom(LogBloom const& _v) { m_logBloom = _v; noteDirty(); }
diff --git a/test/libethcore/difficulty.cpp b/test/libethcore/difficulty.cpp
new file mode 100644
index 000000000..6defcd51d
--- /dev/null
+++ b/test/libethcore/difficulty.cpp
@@ -0,0 +1,62 @@
+/*
+	This file is part of cpp-ethereum.
+
+	cpp-ethereum is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	cpp-ethereum is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/** @file difficulty.cpp
+ * @author Christoph Jentzsch <cj@ethdev.com>
+ * @date 2015
+ * difficulty calculation tests.
+ */
+
+
+#include <boost/test/unit_test.hpp>
+#include <test/TestHelper.h>
+#include <libethcore/BlockInfo.h>
+
+using namespace std;
+using namespace dev;
+using namespace dev::eth;
+
+namespace js = json_spirit;
+
+BOOST_AUTO_TEST_SUITE(DifficultyTests)
+
+BOOST_AUTO_TEST_CASE(difficultyTests)
+{
+	string testPath = test::getTestPath();
+	testPath += "/BasicTests";
+
+	js::mValue v;
+	string s = contentsString(testPath + "/difficulty.json");
+	BOOST_REQUIRE_MESSAGE(s.length() > 0, "Contents of 'difficulty.json' is empty. Have you cloned the 'tests' repo branch develop?");
+	js::read_string(s, v);
+
+	for (auto& i: v.get_obj())
+	{
+		js::mObject o = i.second.get_obj();
+		cnote << "Difficulty test: " << i.first;
+		BlockInfo parent;
+		parent.setTimestamp(test::toInt(o["parentTimestamp"]));
+		parent.setDifficulty(test::toInt(o["parentDifficulty"]));
+
+		BlockInfo current;
+		current.setTimestamp(test::toInt(o["currentTimestamp"]));
+		current.setNumber(test::toInt(o["currentBlockNumber"]));
+
+		BOOST_CHECK_EQUAL(current.calculateDifficulty(parent), test::toInt(o["currentDifficulty"]));
+	}
+}
+
+BOOST_AUTO_TEST_SUITE_END()