diff --git a/src/Makefile.test.include b/src/Makefile.test.include
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -105,7 +105,8 @@
   test/undo_tests.cpp \
   test/univalue_tests.cpp \
   test/util_tests.cpp \
-  test/validation_tests.cpp
+  test/validation_tests.cpp \
+  test/work_comparator_tests.cpp
 
 if ENABLE_WALLET
 BITCOIN_TESTS += \
diff --git a/src/test/CMakeLists.txt b/src/test/CMakeLists.txt
--- a/src/test/CMakeLists.txt
+++ b/src/test/CMakeLists.txt
@@ -117,6 +117,7 @@
 	univalue_tests.cpp
 	util_tests.cpp
 	validation_tests.cpp
+	work_comparator_tests.cpp
 
 	# Tests generated from JSON
 	${JSON_HEADERS}
diff --git a/src/test/work_comparator_tests.cpp b/src/test/work_comparator_tests.cpp
new file mode 100644
--- /dev/null
+++ b/src/test/work_comparator_tests.cpp
@@ -0,0 +1,58 @@
+// Copyright (c) 2018 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "blockindexworkcomparator.h"
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_AUTO_TEST_SUITE(work_comparator_tests)
+
+BOOST_AUTO_TEST_CASE(work_comparator) {
+    CBlockIndex indexA, indexB;
+
+    // Differing chain work
+    indexA.nChainWork = 0;
+    indexB.nChainWork = 1;
+    for (int sequenceIdA = 1; sequenceIdA < 1024; sequenceIdA *= 2) {
+        for (int sequenceIdB = 1; sequenceIdB < 1024; sequenceIdB *= 2) {
+            // Differing sequenceId doesn't affect chain work
+            indexA.nSequenceId = sequenceIdA;
+            indexB.nSequenceId = sequenceIdB;
+            BOOST_CHECK(CBlockIndexWorkComparator()(&indexA, &indexB));
+        }
+    }
+
+    // Same chain work, but differing sequenceId
+    indexA = CBlockIndex();
+    indexB = CBlockIndex();
+    for (int sequenceIdA = 1; sequenceIdA < 1024; sequenceIdA *= 2) {
+        for (int sequenceIdB = 1; sequenceIdB < 1024; sequenceIdB *= 2) {
+            if (sequenceIdA == sequenceIdB) {
+                continue;
+            }
+
+            indexA.nSequenceId = sequenceIdA;
+            indexB.nSequenceId = sequenceIdB;
+            if (sequenceIdA > sequenceIdB) {
+                BOOST_CHECK(CBlockIndexWorkComparator()(&indexA, &indexB));
+            } else {
+                BOOST_CHECK(CBlockIndexWorkComparator()(&indexB, &indexA));
+            }
+        }
+    }
+
+    // All else equal, so checking pointer address as final check
+    CBlockIndex *pindexA = new CBlockIndex();
+    CBlockIndex *pindexB = new CBlockIndex();
+    if (pindexA < pindexB) {
+        BOOST_CHECK(CBlockIndexWorkComparator()(pindexB, pindexA));
+    } else {
+        BOOST_CHECK(CBlockIndexWorkComparator()(pindexA, pindexB));
+    }
+
+    // Same block should return false
+    BOOST_CHECK(!CBlockIndexWorkComparator()(pindexA, pindexA));
+}
+
+BOOST_AUTO_TEST_SUITE_END()