diff --git a/src/Makefile.test.include b/src/Makefile.test.include
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -130,7 +130,8 @@
   test/uint256_tests.cpp \
   test/undo_tests.cpp \
   test/univalue_tests.cpp \
-  test/util_tests.cpp
+  test/util_tests.cpp \
+  test/validation_tests.cpp
 
 if ENABLE_WALLET
 BITCOIN_TESTS += \
diff --git a/src/test/validation_tests.cpp b/src/test/validation_tests.cpp
new file mode 100644
--- /dev/null
+++ b/src/test/validation_tests.cpp
@@ -0,0 +1,74 @@
+// Copyright (c) 2011-2016 The Bitcoin Core developers
+// Copyright (c) 2017 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "validation.h"
+#include "chainparams.h"
+#include "config.h"
+#include "consensus/consensus.h"
+#include "primitives/transaction.h"
+#include "test/test_bitcoin.h"
+#include "util.h"
+
+#include <cstdint>
+#include <cstdio>
+#include <vector>
+
+#include <boost/test/unit_test.hpp>
+
+static CBlock makeLargeDummyBlock(const size_t num_tx) {
+    CBlock block;
+    block.vtx.reserve(num_tx);
+
+    CTransaction tx;
+    for (size_t i = 0; i < num_tx; i++) {
+        block.vtx.push_back(MakeTransactionRef(tx));
+    }
+    return block;
+}
+
+BOOST_FIXTURE_TEST_SUITE(validation_tests, BasicTestingSetup)
+
+/** Test that LoadExternalBlockFile works with the buffer size set
+below the size of a large block. Currently, LoadExternalBlockFile has the
+buffer size for CBufferedFile set to 2 * MAX_TX_SIZE. Test with a value
+of 10 * MAX_TX_SIZE. */
+BOOST_AUTO_TEST_CASE(validation_load_external_block_file) {
+    FILE *fp = tmpfile();
+
+    const Config &config = GetConfig();
+    const CChainParams &chainparams = config.GetChainParams();
+
+    // serialization format is:
+    // message start magic, size of block, block
+
+    size_t nwritten = fwrite(chainparams.MessageStart(),
+                             CMessageHeader::MESSAGE_START_SIZE, 1, fp);
+
+    BOOST_CHECK_EQUAL(nwritten, 1);
+
+    CTransaction empty_tx;
+    size_t empty_tx_size = GetSerializeSize(empty_tx, SER_DISK, CLIENT_VERSION);
+
+    size_t num_tx = (10 * MAX_TX_SIZE) / empty_tx_size;
+
+    CBlock block = makeLargeDummyBlock(num_tx);
+
+    BOOST_CHECK(GetSerializeSize(block, SER_DISK, CLIENT_VERSION) >
+                2 * MAX_TX_SIZE);
+
+    unsigned int size = GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
+    {
+        CAutoFile outs(fp, SER_DISK, CLIENT_VERSION);
+        outs << size;
+        outs << block;
+        outs.release();
+    }
+
+    fseek(fp, 0, SEEK_SET);
+    BOOST_CHECK_NO_THROW(
+        { LoadExternalBlockFile(config, chainparams, fp, 0); });
+}
+
+BOOST_AUTO_TEST_SUITE_END()