diff --git a/src/slack-timedate.cpp b/src/slack-timedate.cpp
index cc48ce8..e800236 100644
--- a/src/slack-timedate.cpp
+++ b/src/slack-timedate.cpp
@@ -85,8 +85,9 @@ static void slack_method_call (GDBusConnection *connection, const gchar *sender,
 	}
     else if (g_strcmp0(method_name, "ListTimezones") == 0)
     {
-        auto return_value = Glib::Variant<std::vector<Glib::ustring>>::create({});
-        auto return_tuple = Glib::Variant<std::vector<Glib::ustring>>::create_tuple({ return_value });
+        auto return_tuple = Glib::Variant<std::vector<Glib::ustring>>::create_tuple({
+                dlackware::timedate::list_timezones()
+        });
 
         g_dbus_method_invocation_return_value(invocation, return_tuple.gobj());
     }
@@ -165,6 +166,39 @@ int main(int argc, char **argv)
 	return EXIT_SUCCESS;
 }
 
+namespace dlackware::timedate
+{
+    void list_timezones(const std::string& prefix, std::vector<Glib::ustring>& accumulator)
+    {
+        Glib::FileTest is_directory = Glib::FILE_TEST_IS_DIR;
+        Glib::FileTest is_regular = Glib::FILE_TEST_IS_REGULAR;
+        auto zoneinfo_path = std::filesystem::path(zoneinfo_database) / prefix;
+        auto zoneinfo_directory = Glib::Dir(zoneinfo_path);
+
+        for (auto zoneinfo_entry : zoneinfo_directory)
+        {
+            auto entry_path = zoneinfo_path / zoneinfo_entry;
+
+            if (Glib::file_test(entry_path, is_directory))
+            {
+                list_timezones(prefix + zoneinfo_entry + "/", accumulator);
+            }
+            else if (Glib::file_test(entry_path, is_regular) && !entry_path.has_extension()
+                    && zoneinfo_entry != "leapseconds")
+            {
+                accumulator.push_back(prefix + zoneinfo_entry);
+            }
+        }
+    }
+
+    Glib::Variant<std::vector<Glib::ustring>> list_timezones()
+    {
+        std::vector<Glib::ustring> result;
+
+        list_timezones("", result);
+        return Glib::Variant<std::vector<Glib::ustring>>::create(result);
+    }
+}
 
 gchar *slack_get_timezone () {
 	gchar *zone_copied_from, *zone;
diff --git a/src/slack-timedate.h b/src/slack-timedate.h
index 72fcc2d..61ee8d5 100644
--- a/src/slack-timedate.h
+++ b/src/slack-timedate.h
@@ -59,6 +59,13 @@
 constexpr gint32 USEC_PER_SEC = 1000000ULL;
 constexpr gint32 NSEC_PER_USEC = 1000ULL;
 
+namespace dlackware::timedate
+{
+    constexpr const char *zoneinfo_database = "/usr/share/zoneinfo";
+
+    Glib::Variant<std::vector<Glib::ustring>> list_timezones();
+}
+
 // Returns the system time zone
 gchar *slack_get_timezone ();