diff --git a/src/test/mempool_tests.cpp b/src/test/mempool_tests.cpp
--- a/src/test/mempool_tests.cpp
+++ b/src/test/mempool_tests.cpp
@@ -1042,6 +1042,45 @@
     pool.GetTransactionAncestry(ty6->GetId(), ancestors, descendants);
     BOOST_CHECK_EQUAL(ancestors, 9ULL);
     BOOST_CHECK_EQUAL(descendants, 6ULL);
+
+    /* Ancestors represented more than once ("diamond") */
+    //
+    // [ta].0 <- [tb].0 -----<------- [td].0
+    //            |                    |
+    //            \---1 <- [tc].0 --<--/
+    //
+    CTransactionRef ta, tb, tc, td;
+    ta = make_tx(/* output_values */ {10 * COIN});
+    tb = make_tx(/* output_values */ {5 * COIN, 3 * COIN}, /* inputs */ {ta});
+    tc = make_tx(/* output_values */ {2 * COIN}, /* inputs */ {tb},
+                 /* input_indices */ {1});
+    td = make_tx(/* output_values */ {6 * COIN}, /* inputs */ {tb, tc},
+                 /* input_indices */ {0, 0});
+    pool.clear();
+    pool.addUnchecked(entry.Fee(10000 * SATOSHI).FromTx(ta));
+    pool.addUnchecked(entry.Fee(10000 * SATOSHI).FromTx(tb));
+    pool.addUnchecked(entry.Fee(10000 * SATOSHI).FromTx(tc));
+    pool.addUnchecked(entry.Fee(10000 * SATOSHI).FromTx(td));
+
+    // Ancestors / descendants should be:
+    // transaction  ancestors           descendants
+    // ============ =================== ===========
+    // ta           1 (ta               4 (ta,tb,tc,td)
+    // tb           2 (ta,tb)           4 (ta,tb,tc,td)
+    // tc           3 (ta,tb,tc)        4 (ta,tb,tc,td)
+    // td           4 (ta,tb,tc,td)     4 (ta,tb,tc,td)
+    pool.GetTransactionAncestry(ta->GetId(), ancestors, descendants);
+    BOOST_CHECK_EQUAL(ancestors, 1ULL);
+    BOOST_CHECK_EQUAL(descendants, 4ULL);
+    pool.GetTransactionAncestry(tb->GetId(), ancestors, descendants);
+    BOOST_CHECK_EQUAL(ancestors, 2ULL);
+    BOOST_CHECK_EQUAL(descendants, 4ULL);
+    pool.GetTransactionAncestry(tc->GetId(), ancestors, descendants);
+    BOOST_CHECK_EQUAL(ancestors, 3ULL);
+    BOOST_CHECK_EQUAL(descendants, 4ULL);
+    pool.GetTransactionAncestry(td->GetId(), ancestors, descendants);
+    BOOST_CHECK_EQUAL(ancestors, 4ULL);
+    BOOST_CHECK_EQUAL(descendants, 4ULL);
 }
 
 BOOST_AUTO_TEST_SUITE_END()