diff --git a/tests/sstable_assertions.hh b/tests/sstable_assertions.hh
new file mode 100644
index 0000000000..4379f2cad1
--- /dev/null
+++ b/tests/sstable_assertions.hh
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2017 ScyllaDB
+ */
+
+/*
+ * This file is part of Scylla.
+ *
+ * Scylla is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Scylla 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 Scylla.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "dht/i_partitioner.hh"
+#include "schema.hh"
+#include "sstables/index_reader.hh"
+
+class index_reader_assertions {
+    std::unique_ptr<sstables::index_reader> _r;
+public:
+    index_reader_assertions(std::unique_ptr<sstables::index_reader> r)
+        : _r(std::move(r))
+    { }
+
+    index_reader_assertions& has_monotonic_positions(const schema& s) {
+        auto pos_cmp = position_in_partition::composite_less_compare(s);
+        auto rp_cmp = dht::ring_position_comparator(s);
+        auto prev = dht::ring_position::min();
+        _r->read_partition_data().get();
+        while (!_r->eof()) {
+            auto k = _r->current_partition_entry().get_decorated_key();
+            auto rp = dht::ring_position(k.token(), k.key().to_partition_key(s));
+
+            if (!rp_cmp(prev, rp)) {
+                BOOST_FAIL(sprint("Partitions have invalid order: %s >= %s", prev, rp));
+            }
+
+            prev = rp;
+
+            auto* pi = _r->current_partition_entry().get_promoted_index(s);
+            if (!pi->entries.empty()) {
+                auto& prev = pi->entries[0];
+                for (size_t i = 1; i < pi->entries.size(); ++i) {
+                    auto& cur = pi->entries[i];
+                    if (!pos_cmp(prev.end, cur.start)) {
+                        std::cout << "promoted index:\n";
+                        for (auto& e : pi->entries) {
+                            std::cout << "  " << e.start << "-" << e.end << ": +" << e.offset << " len=" << e.width << std::endl;
+                        }
+                        BOOST_FAIL(sprint("Index blocks are not monotonic: %s >= %s", prev.end, cur.start));
+                    }
+                    cur = prev;
+                }
+            }
+            _r->advance_to_next_partition().get();
+        }
+        return *this;
+    }
+};
+
+inline
+index_reader_assertions assert_that(std::unique_ptr<sstables::index_reader> r) {
+    return { std::move(r) };
+}
diff --git a/tests/sstable_mutation_test.cc b/tests/sstable_mutation_test.cc
index 6bdcddd240..c33cd210e3 100644
--- a/tests/sstable_mutation_test.cc
+++ b/tests/sstable_mutation_test.cc
@@ -35,6 +35,7 @@
 #include "tmpdir.hh"
 #include "memtable-sstable.hh"
 #include "disk-error-handler.hh"
+#include "tests/sstable_assertions.hh"
 
 thread_local disk_error_signal_type commit_error;
 thread_local disk_error_signal_type general_disk_error;
@@ -801,3 +802,52 @@ SEASTAR_TEST_CASE(test_non_compound_table_row_is_not_marked_as_static) {
         BOOST_REQUIRE(bool(mut));
     });
 }
+
+SEASTAR_TEST_CASE(test_promoted_index_blocks_are_monotonic) {
+    return seastar::async([] {
+        auto dir = make_lw_shared<tmpdir>();
+        schema_builder builder("ks", "cf");
+        builder.with_column("p", utf8_type, column_kind::partition_key);
+        builder.with_column("c1", int32_type, column_kind::clustering_key);
+        builder.with_column("c2", int32_type, column_kind::clustering_key);
+        builder.with_column("v", int32_type);
+        auto s = builder.build();
+
+        auto k = partition_key::from_exploded(*s, {to_bytes("key1")});
+        auto cell = atomic_cell::make_live(1, int32_type->decompose(88), { });
+        mutation m(k, s);
+
+        auto ck = clustering_key::from_exploded(*s, {int32_type->decompose(1), int32_type->decompose(2)});
+        m.set_clustered_cell(ck, *s->get_column_definition("v"), cell);
+
+        ck = clustering_key::from_exploded(*s, {int32_type->decompose(1), int32_type->decompose(4)});
+        m.set_clustered_cell(ck, *s->get_column_definition("v"), std::move(cell));
+
+        ck = clustering_key::from_exploded(*s, {int32_type->decompose(1), int32_type->decompose(6)});
+        m.set_clustered_cell(ck, *s->get_column_definition("v"), std::move(cell));
+
+        ck = clustering_key::from_exploded(*s, {int32_type->decompose(3), int32_type->decompose(9)});
+        m.set_clustered_cell(ck, *s->get_column_definition("v"), std::move(cell));
+
+        m.partition().apply_row_tombstone(*s, range_tombstone(
+                clustering_key_prefix::from_exploded(*s, {int32_type->decompose(1)}),
+                bound_kind::excl_start,
+                clustering_key_prefix::from_exploded(*s, {int32_type->decompose(2)}),
+                bound_kind::incl_end,
+                {1, gc_clock::now()}));
+
+        auto mt = make_lw_shared<memtable>(s);
+        mt->apply(std::move(m));
+
+        auto sst = make_lw_shared<sstables::sstable>(s,
+                                dir->path,
+                                1 /* generation */,
+                                sstables::sstable::version_types::ka,
+                                sstables::sstable::format_types::big);
+        sstable_writer_config cfg;
+        cfg.promoted_index_block_size = 1;
+        sst->write_components(mt->make_reader(s), 1, s, cfg).get();
+        sst->load().get();
+        assert_that(sst->get_index_reader(default_priority_class())).has_monotonic_positions(*s);
+    });
+}