diff --git a/extern/assert b/extern/assert
index 2cd99e24e..6aabfebae 160000
--- a/extern/assert
+++ b/extern/assert
@@ -1 +1 @@
-Subproject commit 2cd99e24e834d600d51cf3b8cdc3df6ecfd8e9f1
+Subproject commit 6aabfebae6d4acf996fe711de4e9b444ad88c17d
diff --git a/extern/config b/extern/config
index fad75493b..088b79a0c 160000
--- a/extern/config
+++ b/extern/config
@@ -1 +1 @@
-Subproject commit fad75493bd2da03524854976f2d80dd7989c90fb
+Subproject commit 088b79a0ca751932010f82d3f95457c8b483fb9b
diff --git a/extern/core b/extern/core
index ca4893063..f4b3d5dba 160000
--- a/extern/core
+++ b/extern/core
@@ -1 +1 @@
-Subproject commit ca4893063fa244a690b1f799328f16408b794c77
+Subproject commit f4b3d5dba6f86caaf96e45901655a954b2ff68b4
diff --git a/extern/histogram b/extern/histogram
index 7c24d2683..4a10c2c11 160000
--- a/extern/histogram
+++ b/extern/histogram
@@ -1 +1 @@
-Subproject commit 7c24d2683e6be78cda90dcc0026ceeb7b5131507
+Subproject commit 4a10c2c11b272f435f61233eb9f585604476b2f8
diff --git a/extern/mp11 b/extern/mp11
index 21cace4e5..9d43d1f69 160000
--- a/extern/mp11
+++ b/extern/mp11
@@ -1 +1 @@
-Subproject commit 21cace4e574180ba64d9307a5e4ea9e5e94d3e8d
+Subproject commit 9d43d1f69660617266c9168e6e121ab2b0ea2287
diff --git a/extern/throw_exception b/extern/throw_exception
index da6f5420f..95e02ea52 160000
--- a/extern/throw_exception
+++ b/extern/throw_exception
@@ -1 +1 @@
-Subproject commit da6f5420fe7e96f673ee185c2ff37cbaa3f95b84
+Subproject commit 95e02ea52b8525ecf34dbf1e7fae34af09986b8a
diff --git a/extern/variant2 b/extern/variant2
index 1ebc29aa0..4153a535a 160000
--- a/extern/variant2
+++ b/extern/variant2
@@ -1 +1 @@
-Subproject commit 1ebc29aa0277cbb284a70327b5af14519f2702bc
+Subproject commit 4153a535a0fa8eb4d18abc262fcf2ae834601261
diff --git a/include/bh_python/accumulators/ostream.hpp b/include/bh_python/accumulators/ostream.hpp
index 03e251582..2140d5a26 100644
--- a/include/bh_python/accumulators/ostream.hpp
+++ b/include/bh_python/accumulators/ostream.hpp
@@ -79,7 +79,7 @@ std::basic_ostream<CharT, Traits>& operator<<(std::basic_ostream<CharT, Traits>&
 template <class CharT, class Traits, class T>
 std::basic_ostream<CharT, Traits>&
 operator<<(std::basic_ostream<CharT, Traits>& os,
-           const ::boost::histogram::accumulators::thread_safe<T>& x) {
+           const ::boost::histogram::accumulators::count<T, true>& x) {
     os << x.load();
     return os;
 }
diff --git a/include/bh_python/histogram.hpp b/include/bh_python/histogram.hpp
index 0d26afb0f..80125017f 100644
--- a/include/bh_python/histogram.hpp
+++ b/include/bh_python/histogram.hpp
@@ -20,8 +20,8 @@ namespace pybind11 {
 /// The descriptor for atomic_* is the same as the descriptor for *, as long this uses
 /// standard layout
 template <class T>
-struct format_descriptor<bh::accumulators::thread_safe<T>> : format_descriptor<T> {
-    static_assert(std::is_standard_layout<bh::accumulators::thread_safe<T>>::value, "");
+struct format_descriptor<bh::accumulators::count<T, true>> : format_descriptor<T> {
+    static_assert(std::is_standard_layout<bh::accumulators::count<T, true>>::value, "");
 };
 
 } // namespace pybind11
diff --git a/include/bh_python/storage.hpp b/include/bh_python/storage.hpp
index bcbdd5bd2..75646e0c0 100644
--- a/include/bh_python/storage.hpp
+++ b/include/bh_python/storage.hpp
@@ -11,7 +11,7 @@
 #include <bh_python/accumulators/weighted_mean.hpp>
 #include <bh_python/accumulators/weighted_sum.hpp>
 
-#include <boost/histogram/accumulators/thread_safe.hpp>
+#include <boost/histogram/accumulators/count.hpp>
 #include <boost/histogram/storage_adaptor.hpp>
 #include <boost/histogram/unlimited_storage.hpp>
 
@@ -23,7 +23,7 @@ namespace storage {
 
 // Names match Python names
 using int64         = bh::dense_storage<uint64_t>;
-using atomic_int64  = bh::dense_storage<bh::accumulators::thread_safe<uint64_t>>;
+using atomic_int64  = bh::dense_storage<bh::accumulators::count<uint64_t, true>>;
 using double_       = bh::dense_storage<double>;
 using unlimited     = bh::unlimited_storage<>;
 using weight        = bh::dense_storage<accumulators::weighted_sum<double>>;
@@ -80,8 +80,12 @@ template <class Archive>
 void save(Archive& ar, const storage::atomic_int64& s, unsigned /* version */) {
     // We cannot view the memory as a numpy array, because the internal layout of
     // std::atomic is undefined. So no reinterpret_casts are allowed.
-    py::array_t<std::int64_t> a(static_cast<py::ssize_t>(s.size()));
-    std::copy(s.begin(), s.end(), a.mutable_data());
+    py::array_t<std::uint64_t> a(static_cast<py::ssize_t>(s.size()));
+
+    auto in_ptr  = s.begin();
+    auto out_ptr = a.mutable_data();
+    for(; in_ptr != s.end(); ++in_ptr, ++out_ptr)
+        *out_ptr = in_ptr->value();
     ar << a;
 }
 
@@ -187,7 +191,7 @@ struct type_caster<storage::atomic_int64::value_type> {
         auto ptr = PyNumber_Long(src.ptr());
         if(!ptr)
             return false;
-        value.store(PyLong_AsUnsignedLongLong(ptr));
+        value = PyLong_AsUnsignedLongLong(ptr);
         Py_DECREF(ptr);
         return !PyErr_Occurred();
     }
@@ -195,7 +199,7 @@ struct type_caster<storage::atomic_int64::value_type> {
     static handle cast(storage::atomic_int64::value_type src,
                        return_value_policy /* policy */,
                        handle /* parent */) {
-        return PyLong_FromUnsignedLongLong(src.load());
+        return PyLong_FromUnsignedLongLong(src.value());
     }
 };
 } // namespace detail