diff --git a/database.hh b/database.hh
index 543e03e215..7def058a00 100644
--- a/database.hh
+++ b/database.hh
@@ -137,7 +137,7 @@ private:
     // generation -> sstable. Ordered by key so we can easily get the most recent.
     lw_shared_ptr<sstable_list> _sstables;
     mutable row_cache _cache; // Cache covers only sstables.
-    unsigned _sstable_generation = 1;
+    int64_t _sstable_generation = 1;
     unsigned _mutation_count = 0;
     db::replay_position _highest_flushed_rp;
     // Provided by the database that owns this commitlog
diff --git a/sstables/sstables.cc b/sstables/sstables.cc
index 3bff5f7afc..5bf2687836 100644
--- a/sstables/sstables.cc
+++ b/sstables/sstables.cc
@@ -1412,7 +1412,7 @@ sstring sstable::toc_filename() const {
     return filename(component_type::TOC);
 }
 
-const sstring sstable::filename(sstring dir, sstring ks, sstring cf, version_types version, unsigned long generation,
+const sstring sstable::filename(sstring dir, sstring ks, sstring cf, version_types version, int64_t generation,
                                 format_types format, component_type component) {
 
     static std::unordered_map<version_types, std::function<sstring (entry_descriptor d)>, enum_hash<version_types>> strmap = {
@@ -1658,7 +1658,7 @@ file_exists(sstring filename) {
 }
 
 future<>
-sstable::remove_sstable_with_temp_toc(sstring ks, sstring cf, sstring dir, unsigned long generation, version_types v, format_types f) {
+sstable::remove_sstable_with_temp_toc(sstring ks, sstring cf, sstring dir, int64_t generation, version_types v, format_types f) {
     return seastar::async([ks, cf, dir, generation, v, f] {
         auto toc = file_exists(filename(dir, ks, cf, v, generation, f, component_type::TOC)).get0();
         // assert that toc doesn't exist for sstable with temporary toc.
diff --git a/sstables/sstables.hh b/sstables/sstables.hh
index 3bd84990c7..db2733d2ff 100644
--- a/sstables/sstables.hh
+++ b/sstables/sstables.hh
@@ -126,7 +126,7 @@ public:
     enum class version_types { ka, la };
     enum class format_types { big };
 public:
-    sstable(sstring ks, sstring cf, sstring dir, unsigned long generation, version_types v, format_types f, gc_clock::time_point now = gc_clock::now())
+    sstable(sstring ks, sstring cf, sstring dir, int64_t generation, version_types v, format_types f, gc_clock::time_point now = gc_clock::now())
         : _ks(std::move(ks))
         , _cf(std::move(cf))
         , _dir(std::move(dir))
@@ -175,20 +175,20 @@ public:
     static component_type component_from_sstring(sstring& s);
     static version_types version_from_sstring(sstring& s);
     static format_types format_from_sstring(sstring& s);
-    static const sstring filename(sstring dir, sstring ks, sstring cf, version_types version, unsigned long generation,
+    static const sstring filename(sstring dir, sstring ks, sstring cf, version_types version, int64_t generation,
                                   format_types format, component_type component);
     // WARNING: it should only be called to remove components of a sstable with
     // a temporary TOC file.
-    static future<> remove_sstable_with_temp_toc(sstring ks, sstring cf, sstring dir, unsigned long generation,
+    static future<> remove_sstable_with_temp_toc(sstring ks, sstring cf, sstring dir, int64_t generation,
                                                  version_types v, format_types f);
 
     future<> load();
     future<> open_data();
 
-    void set_generation(unsigned long generation) {
+    void set_generation(int64_t generation) {
         _generation = generation;
     }
-    unsigned long generation() const {
+    int64_t generation() const {
         return _generation;
     }
 
@@ -239,7 +239,7 @@ public:
         return _marked_for_deletion;
     }
 
-    void add_ancestor(int generation) {
+    void add_ancestor(int64_t generation) {
         _collector.add_ancestor(generation);
     }
 
@@ -306,7 +306,7 @@ public:
     std::vector<sstring> component_filenames() const;
 
 private:
-    sstable(size_t wbuffer_size, sstring ks, sstring cf, sstring dir, unsigned long generation, version_types v, format_types f, gc_clock::time_point now = gc_clock::now())
+    sstable(size_t wbuffer_size, sstring ks, sstring cf, sstring dir, int64_t generation, version_types v, format_types f, gc_clock::time_point now = gc_clock::now())
         : sstable_buffer_size(wbuffer_size)
         , _ks(std::move(ks))
         , _cf(std::move(cf))
@@ -506,20 +506,20 @@ public:
 };
 
 using shared_sstable = lw_shared_ptr<sstable>;
-using sstable_list = std::map<unsigned long, shared_sstable>;
+using sstable_list = std::map<int64_t, shared_sstable>;
 
 struct entry_descriptor {
     sstring ks;
     sstring cf;
     sstable::version_types version;
-    unsigned long generation;
+    int64_t generation;
     sstable::format_types format;
     sstable::component_type component;
 
     static entry_descriptor make_descriptor(sstring fname);
 
     entry_descriptor(sstring ks, sstring cf, sstable::version_types version,
-                     unsigned long generation, sstable::format_types format,
+                     int64_t generation, sstable::format_types format,
                      sstable::component_type component)
         : ks(ks), cf(cf), version(version), generation(generation), format(format), component(component) {}
 };
diff --git a/tests/sstable_datafile_test.cc b/tests/sstable_datafile_test.cc
index 762a98172d..d7846c383f 100644
--- a/tests/sstable_datafile_test.cc
+++ b/tests/sstable_datafile_test.cc
@@ -1612,7 +1612,7 @@ static std::vector<std::pair<sstring, dht::token>> token_generation_for_current_
     return key_and_token_pair;
 }
 
-static void add_sstable_for_leveled_test(lw_shared_ptr<column_family>& cf, unsigned long gen, uint64_t fake_data_size,
+static void add_sstable_for_leveled_test(lw_shared_ptr<column_family>& cf, int64_t gen, uint64_t fake_data_size,
                                          uint32_t sstable_level, sstring first_key, sstring last_key, int64_t max_timestamp = 0) {
     auto sst = make_lw_shared<sstable>("ks", "cf", "", gen, la, big);
     sstables::test(sst).set_values_for_leveled_strategy(fake_data_size, sstable_level, max_timestamp, std::move(first_key), std::move(last_key));
@@ -1631,7 +1631,7 @@ static bool key_range_overlaps(sstring a, sstring b, sstring c, sstring d) {
     return range1.overlaps(range2, dht::token_comparator());
 }
 
-static shared_sstable get_sstable(const lw_shared_ptr<column_family>& cf, unsigned long generation) {
+static shared_sstable get_sstable(const lw_shared_ptr<column_family>& cf, int64_t generation) {
     auto sstables = cf->get_sstables();
     auto entry = sstables->find(generation);
     assert(entry != sstables->end());
@@ -1640,7 +1640,7 @@ static shared_sstable get_sstable(const lw_shared_ptr<column_family>& cf, unsign
     return entry->second;
 }
 
-static bool sstable_overlaps(const lw_shared_ptr<column_family>& cf, unsigned long gen1, unsigned long gen2) {
+static bool sstable_overlaps(const lw_shared_ptr<column_family>& cf, int64_t gen1, int64_t gen2) {
     const schema& s = *cf->schema();
     auto candidate1 = get_sstable(cf, gen1);
     auto range1 = range<dht::token>::make(candidate1->get_first_decorated_key(s)._token, candidate1->get_last_decorated_key(s)._token);