diff --git a/include/boost/unordered/concurrent_flat_map.hpp b/include/boost/unordered/concurrent_flat_map.hpp
index 10bfbba5..952cb873 100644
--- a/include/boost/unordered/concurrent_flat_map.hpp
+++ b/include/boost/unordered/concurrent_flat_map.hpp
@@ -39,26 +39,26 @@
 
 #define BOOST_UNORDERED_COMMA ,
 
-#define BOOST_UNORDERED_LAST_ARG(Arg, Args)                                     \
-mp11::mp_back<mp11::mp_list<Arg BOOST_UNORDERED_COMMA Args>>
+#define BOOST_UNORDERED_LAST_ARG(Arg, Args)                                    \
+  mp11::mp_back<mp11::mp_list<Arg BOOST_UNORDERED_COMMA Args> >
 
-#define BOOST_UNORDERED_STATIC_ASSERT_LAST_ARG_INVOCABLE(Arg, Args)             \
-BOOST_UNORDERED_STATIC_ASSERT_INVOCABLE(BOOST_UNORDERED_LAST_ARG(Arg, Args))
+#define BOOST_UNORDERED_STATIC_ASSERT_LAST_ARG_INVOCABLE(Arg, Args)            \
+  BOOST_UNORDERED_STATIC_ASSERT_INVOCABLE(BOOST_UNORDERED_LAST_ARG(Arg, Args))
 
-#define BOOST_UNORDERED_STATIC_ASSERT_LAST_ARG_CONST_INVOCABLE(Arg, Args)       \
-BOOST_UNORDERED_STATIC_ASSERT_CONST_INVOCABLE(                                  \
-  BOOST_UNORDERED_LAST_ARG(Arg, Args))
+#define BOOST_UNORDERED_STATIC_ASSERT_LAST_ARG_CONST_INVOCABLE(Arg, Args)      \
+  BOOST_UNORDERED_STATIC_ASSERT_CONST_INVOCABLE(                               \
+    BOOST_UNORDERED_LAST_ARG(Arg, Args))
 
 namespace boost {
   namespace unordered {
     namespace detail {
+
       template <class F, class... Args>
-      struct is_invocable:
-        std::is_constructible<
-          std::function<void(Args...)>,
-          std::reference_wrapper<typename std::remove_reference<F>::type>
-        >
-      {};
+      struct is_invocable
+          : std::is_constructible<std::function<void(Args...)>,
+              std::reference_wrapper<typename std::remove_reference<F>::type> >
+      {
+      };
 
       template <class Key, class T> struct concurrent_map_types
       {
@@ -142,7 +142,11 @@ namespace boost {
       using const_pointer =
         typename boost::allocator_const_pointer<allocator_type>::type;
 
-      concurrent_flat_map() : concurrent_flat_map(0) {}
+      concurrent_flat_map()
+          : concurrent_flat_map(detail::foa::default_bucket_count)
+      {
+      }
+
       explicit concurrent_flat_map(size_type n, const hasher& hf = hasher(),
         const key_equal& eql = key_equal(),
         const allocator_type& a = allocator_type())
@@ -150,6 +154,23 @@ namespace boost {
       {
       }
 
+      template <class InputIterator>
+      concurrent_flat_map(InputIterator f, InputIterator l,
+        size_type n = detail::foa::default_bucket_count,
+        const hasher& hf = hasher(), const key_equal& eql = key_equal(),
+        const allocator_type& a = allocator_type())
+          : table_(n, hf, eql, a)
+      {
+        this->insert(f, l);
+      }
+
+      concurrent_flat_map(concurrent_flat_map const& rhs)
+          : table_(rhs.table_,
+              boost::allocator_select_on_container_copy_construction(
+                rhs.get_allocator()))
+      {
+      }
+
       /// Capacity
       ///
 
@@ -276,15 +297,13 @@ namespace boost {
 
       template <class M> bool insert_or_assign(key_type const& k, M&& obj)
       {
-        return table_.try_emplace_or_visit(
-          k, std::forward<M>(obj),
+        return table_.try_emplace_or_visit(k, std::forward<M>(obj),
           [&](value_type& m) { m.second = std::forward<M>(obj); });
       }
 
       template <class M> bool insert_or_assign(key_type&& k, M&& obj)
       {
-        return table_.try_emplace_or_visit(
-          std::move(k), std::forward<M>(obj),
+        return table_.try_emplace_or_visit(std::move(k), std::forward<M>(obj),
           [&](value_type& m) { m.second = std::forward<M>(obj); });
       }
 
@@ -293,8 +312,8 @@ namespace boost {
         detail::are_transparent<K, hasher, key_equal>::value, bool>::type
       insert_or_assign(K&& k, M&& obj)
       {
-        return table_.try_emplace_or_visit(
-          std::forward<K>(k), std::forward<M>(obj),
+        return table_.try_emplace_or_visit(std::forward<K>(k),
+          std::forward<M>(obj),
           [&](value_type& m) { m.second = std::forward<M>(obj); });
       }
 
@@ -455,16 +474,16 @@ namespace boost {
       bool try_emplace_or_visit(K&& k, Arg&& arg, Args&&... args)
       {
         BOOST_UNORDERED_STATIC_ASSERT_LAST_ARG_INVOCABLE(Arg, Args...)
-        return table_.try_emplace_or_visit(
-          std::forward<K>(k), std::forward<Arg>(arg), std::forward<Args>(args)...);
+        return table_.try_emplace_or_visit(std::forward<K>(k),
+          std::forward<Arg>(arg), std::forward<Args>(args)...);
       }
 
       template <class K, class Arg, class... Args>
       bool try_emplace_or_cvisit(K&& k, Arg&& arg, Args&&... args)
       {
         BOOST_UNORDERED_STATIC_ASSERT_LAST_ARG_CONST_INVOCABLE(Arg, Args...)
-        return table_.try_emplace_or_cvisit(
-          std::forward<K>(k), std::forward<Arg>(arg), std::forward<Args>(args)...);
+        return table_.try_emplace_or_cvisit(std::forward<K>(k),
+          std::forward<Arg>(arg), std::forward<Args>(args)...);
       }
 
       size_type erase(key_type const& k) { return table_.erase(k); }
@@ -508,6 +527,16 @@ namespace boost {
       ///
       void rehash(size_type n) { table_.rehash(n); }
       void reserve(size_type n) { table_.reserve(n); }
+
+      /// Observers
+      ///
+      allocator_type get_allocator() const noexcept
+      {
+        return table_.get_allocator();
+      }
+
+      hasher hash_function() const { return table_.hash_function(); }
+      key_equal key_eq() const { return table_.key_eq(); }
     };
   } // namespace unordered
 } // namespace boost
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index ca00ff4f..604eedf5 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -175,7 +175,14 @@ alias foa_tests :
   foa_merge_exception_tests
 ;
 
-local CFOA_TESTS = insert_tests erase_tests try_emplace_tests emplace_tests visit_tests ;
+local CFOA_TESTS =
+  insert_tests
+  erase_tests
+  try_emplace_tests
+  emplace_tests
+  visit_tests
+  constructor_tests
+;
 
 for local test in $(CFOA_TESTS)
 {
diff --git a/test/cfoa/constructor_tests.cpp b/test/cfoa/constructor_tests.cpp
new file mode 100644
index 00000000..246a641f
--- /dev/null
+++ b/test/cfoa/constructor_tests.cpp
@@ -0,0 +1,256 @@
+// Copyright (C) 2023 Christian Mazakas
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include "helpers.hpp"
+
+#include <boost/unordered/concurrent_flat_map.hpp>
+
+test::seed_t initialize_seed(4122023);
+
+using test::default_generator;
+using test::limited_range;
+using test::sequential;
+
+using hasher = stateful_hash;
+using key_equal = stateful_key_equal;
+using allocator_type = std::allocator<std::pair<raii const, raii> >;
+
+using map_type = boost::unordered::concurrent_flat_map<raii, raii, hasher,
+  key_equal, allocator_type>;
+
+UNORDERED_AUTO_TEST (default_constructor) {
+  boost::unordered::concurrent_flat_map<raii, raii> x;
+  BOOST_TEST(x.empty());
+  BOOST_TEST_EQ(x.size(), 0u);
+}
+
+UNORDERED_AUTO_TEST (bucket_count_with_hasher_key_equal_and_allocator) {
+  raii::reset_counts();
+  {
+    map_type x(0);
+
+    BOOST_TEST(x.empty());
+    BOOST_TEST_EQ(x.size(), 0u);
+    BOOST_TEST_EQ(x.hash_function(), hasher());
+    BOOST_TEST_EQ(x.key_eq(), key_equal());
+  }
+
+  {
+    map_type x(0, hasher(1));
+
+    BOOST_TEST(x.empty());
+    BOOST_TEST_EQ(x.size(), 0u);
+    BOOST_TEST_EQ(x.hash_function(), hasher(1));
+    BOOST_TEST_EQ(x.key_eq(), key_equal());
+  }
+
+  {
+    map_type x(0, hasher(1), key_equal(2));
+
+    BOOST_TEST(x.empty());
+    BOOST_TEST_EQ(x.size(), 0u);
+    BOOST_TEST_EQ(x.hash_function(), hasher(1));
+    BOOST_TEST_EQ(x.key_eq(), key_equal(2));
+  }
+
+  {
+    map_type x(0, hasher(1), key_equal(2), allocator_type{});
+
+    BOOST_TEST(x.empty());
+    BOOST_TEST_EQ(x.size(), 0u);
+    BOOST_TEST_EQ(x.hash_function(), hasher(1));
+    BOOST_TEST_EQ(x.key_eq(), key_equal(2));
+    BOOST_TEST(x.get_allocator() == allocator_type{});
+  }
+  raii::reset_counts();
+}
+
+namespace {
+  template <class G> void from_iterator_range(G gen, test::random_generator rg)
+  {
+    auto values = make_random_values(1024 * 16, [&] { return gen(rg); });
+    auto reference_map =
+      boost::unordered_flat_map<raii, raii>(values.begin(), values.end());
+    raii::reset_counts();
+
+    {
+      map_type x(values.begin(), values.end());
+
+      test_matches_reference(x, reference_map);
+      BOOST_TEST_GT(x.size(), 0u);
+      BOOST_TEST_LE(x.size(), values.size());
+      BOOST_TEST_EQ(x.hash_function(), hasher());
+      BOOST_TEST_EQ(x.key_eq(), key_equal());
+      BOOST_TEST(x.get_allocator() == allocator_type{});
+      if (rg == sequential) {
+        BOOST_TEST_EQ(x.size(), values.size());
+      }
+      raii::reset_counts();
+    }
+
+    {
+      map_type x(values.begin(), values.end(), 0);
+
+      test_matches_reference(x, reference_map);
+      BOOST_TEST_GT(x.size(), 0u);
+      BOOST_TEST_LE(x.size(), values.size());
+      BOOST_TEST_EQ(x.hash_function(), hasher());
+      BOOST_TEST_EQ(x.key_eq(), key_equal());
+      BOOST_TEST(x.get_allocator() == allocator_type{});
+      if (rg == sequential) {
+        BOOST_TEST_EQ(x.size(), values.size());
+      }
+      raii::reset_counts();
+    }
+
+    {
+      map_type x(values.begin(), values.end(), 0, hasher(1));
+
+      test_matches_reference(x, reference_map);
+      BOOST_TEST_GT(x.size(), 0u);
+      BOOST_TEST_LE(x.size(), values.size());
+      BOOST_TEST_EQ(x.hash_function(), hasher(1));
+      BOOST_TEST_EQ(x.key_eq(), key_equal());
+      BOOST_TEST(x.get_allocator() == allocator_type{});
+      if (rg == sequential) {
+        BOOST_TEST_EQ(x.size(), values.size());
+      }
+      raii::reset_counts();
+    }
+
+    {
+      map_type x(values.begin(), values.end(), 0, hasher(1), key_equal(2));
+
+      test_matches_reference(x, reference_map);
+      BOOST_TEST_GT(x.size(), 0u);
+      BOOST_TEST_LE(x.size(), values.size());
+      BOOST_TEST_EQ(x.hash_function(), hasher(1));
+      BOOST_TEST_EQ(x.key_eq(), key_equal(2));
+      BOOST_TEST(x.get_allocator() == allocator_type{});
+      if (rg == sequential) {
+        BOOST_TEST_EQ(x.size(), values.size());
+      }
+      raii::reset_counts();
+    }
+
+    {
+      map_type x(values.begin(), values.end(), 0, hasher(1), key_equal(2),
+        allocator_type{});
+
+      test_matches_reference(x, reference_map);
+      BOOST_TEST_GT(x.size(), 0u);
+      BOOST_TEST_LE(x.size(), values.size());
+      BOOST_TEST_EQ(x.hash_function(), hasher(1));
+      BOOST_TEST_EQ(x.key_eq(), key_equal(2));
+      BOOST_TEST(x.get_allocator() == allocator_type{});
+      if (rg == sequential) {
+        BOOST_TEST_EQ(x.size(), values.size());
+      }
+      raii::reset_counts();
+    }
+  }
+
+  template <class G> void copy_constructor(G gen, test::random_generator rg)
+  {
+    {
+      map_type x(0, hasher(1), key_equal(2), allocator_type{});
+      map_type y(x);
+
+      BOOST_TEST_EQ(y.size(), x.size());
+      BOOST_TEST_EQ(y.hash_function(), x.hash_function());
+      BOOST_TEST_EQ(y.key_eq(), x.key_eq());
+      BOOST_TEST(y.get_allocator() == x.get_allocator());
+    }
+
+    auto values = make_random_values(1024 * 16, [&] { return gen(rg); });
+    auto reference_map =
+      boost::unordered_flat_map<raii, raii>(values.begin(), values.end());
+    raii::reset_counts();
+
+    {
+      map_type x(values.begin(), values.end(), 0, hasher(1), key_equal(2),
+        allocator_type{});
+
+      thread_runner(
+        values, [&x, &reference_map](
+                  boost::span<typename decltype(values)::value_type> s) {
+          (void)s;
+          map_type y(x);
+
+          test_matches_reference(x, reference_map);
+          test_matches_reference(y, reference_map);
+          BOOST_TEST_EQ(y.size(), x.size());
+          BOOST_TEST_EQ(y.hash_function(), x.hash_function());
+          BOOST_TEST_EQ(y.key_eq(), x.key_eq());
+          BOOST_TEST(y.get_allocator() == x.get_allocator());
+        });
+    }
+  }
+
+  template <class G>
+  void copy_constructor_with_insertion(G gen, test::random_generator rg)
+  {
+    auto values = make_random_values(1024 * 16, [&] { return gen(rg); });
+    auto reference_map =
+      boost::unordered_flat_map<raii, raii>(values.begin(), values.end());
+    raii::reset_counts();
+
+    {
+      map_type x(0, hasher(1), key_equal(2), allocator_type{});
+
+      auto f = [&x, &values] {
+        std::this_thread::sleep_for(std::chrono::milliseconds(75));
+        for (auto const& val : values) {
+          x.insert(val);
+        }
+      };
+
+      std::thread t1(f);
+      std::thread t2(f);
+
+      thread_runner(
+        values, [&x, &reference_map, &values, rg](
+                  boost::span<typename decltype(values)::value_type> s) {
+          (void)s;
+          map_type y(x);
+          BOOST_TEST_GT(y.size(), 0u);
+          BOOST_TEST_LE(y.size(), values.size());
+          BOOST_TEST_EQ(y.hash_function(), x.hash_function());
+          BOOST_TEST_EQ(y.key_eq(), x.key_eq());
+          BOOST_TEST(y.get_allocator() == x.get_allocator());
+
+          x.visit_all([&reference_map, rg](
+                        typename map_type::value_type const& val) {
+            BOOST_TEST(reference_map.contains(val.first));
+            if (rg == sequential) {
+              BOOST_TEST_EQ(val.second, reference_map.find(val.first)->second);
+            }
+          });
+        });
+
+      t1.join();
+      t2.join();
+    }
+  }
+
+} // namespace
+
+// clang-format off
+UNORDERED_TEST(
+  from_iterator_range,
+  ((value_type_generator))
+  ((default_generator)(sequential)(limited_range)))
+
+UNORDERED_TEST(
+  copy_constructor,
+  ((value_type_generator))
+  ((default_generator)(sequential)(limited_range)))
+
+UNORDERED_TEST(
+  copy_constructor_with_insertion,
+  ((value_type_generator))
+  ((default_generator)(sequential)(limited_range)))
+// clang-format on
+
+RUN_TESTS()
diff --git a/test/cfoa/helpers.hpp b/test/cfoa/helpers.hpp
index 8fb4fdd3..01f15ccf 100644
--- a/test/cfoa/helpers.hpp
+++ b/test/cfoa/helpers.hpp
@@ -36,6 +36,67 @@ struct transp_key_equal
   }
 };
 
+struct stateful_hash
+{
+  int x_ = -1;
+
+  stateful_hash() = default;
+  stateful_hash(stateful_hash const&) = default;
+  stateful_hash(stateful_hash&& rhs) noexcept
+  {
+    auto tmp = x_;
+    x_ = rhs.x_;
+    rhs.x_ = tmp;
+  }
+
+  stateful_hash(int const x) : x_{x} {}
+
+  template <class T> std::size_t operator()(T const& t) const noexcept
+  {
+    std::size_t h = static_cast<std::size_t>(x_);
+    boost::hash_combine(h, t);
+    return h;
+  }
+
+  bool operator==(stateful_hash const& rhs) const { return x_ == rhs.x_; }
+
+  friend std::ostream& operator<<(std::ostream& os, stateful_hash const& rhs)
+  {
+    os << "{ x_: " << rhs.x_ << " }";
+    return os;
+  }
+};
+
+struct stateful_key_equal
+{
+  int x_ = -1;
+
+  stateful_key_equal() = default;
+  stateful_key_equal(stateful_key_equal const&) = default;
+  stateful_key_equal(stateful_key_equal&& rhs) noexcept
+  {
+    auto tmp = x_;
+    x_ = rhs.x_;
+    rhs.x_ = tmp;
+  }
+
+  stateful_key_equal(int const x) : x_{x} {}
+
+  template <class T, class U> bool operator()(T const& t, U const& u) const
+  {
+    return t == u;
+  }
+
+  bool operator==(stateful_key_equal const& rhs) const { return x_ == rhs.x_; }
+
+  friend std::ostream& operator<<(
+    std::ostream& os, stateful_key_equal const& rhs)
+  {
+    os << "{ x_: " << rhs.x_ << " }";
+    return os;
+  }
+};
+
 struct raii
 {
   static std::atomic<std::uint32_t> default_constructor;
@@ -226,4 +287,14 @@ template <class T, class F> void thread_runner(std::vector<T>& values, F f)
   }
 }
 
+template <class X, class Y>
+void test_matches_reference(X const& x, Y const& reference_map)
+{
+  using value_type = typename X::value_type;
+  BOOST_TEST_EQ(x.size(), x.visit_all([&](value_type const& kv) {
+    BOOST_TEST(reference_map.contains(kv.first));
+    BOOST_TEST_EQ(kv.second, reference_map.find(kv.first)->second);
+  }));
+}
+
 #endif // BOOST_UNORDERED_TEST_CFOA_HELPERS_HPP
\ No newline at end of file