diff --git a/include/boost/histogram/accumulators/mean.hpp b/include/boost/histogram/accumulators/mean.hpp
index 0bf321ef..f6f15d2a 100644
--- a/include/boost/histogram/accumulators/mean.hpp
+++ b/include/boost/histogram/accumulators/mean.hpp
@@ -30,7 +30,7 @@ class mean {
   using value_type = ValueType;
   using const_reference = const value_type&;
 
-  struct impl_type {
+  struct data_type {
     value_type sum_;
     value_type mean_;
     value_type sum_of_deltas_squared_;
@@ -152,7 +152,7 @@ class mean {
   }
 
 private:
-  impl_type data_{0, 0, 0};
+  data_type data_{0, 0, 0};
 
   friend struct ::boost::histogram::unsafe_access;
 };
diff --git a/include/boost/histogram/unsafe_access.hpp b/include/boost/histogram/unsafe_access.hpp
index 430b643f..4783694d 100644
--- a/include/boost/histogram/unsafe_access.hpp
+++ b/include/boost/histogram/unsafe_access.hpp
@@ -97,8 +97,8 @@ struct unsafe_access {
     Get buffer of unlimited_storage.
     @param storage instance of unlimited_storage.
   */
-  template <class Allocator>
-  static constexpr auto& unlimited_storage_buffer(unlimited_storage<Allocator>& storage) {
+  template <class T>
+  static constexpr auto& unlimited_storage_buffer(T& storage) {
     return storage.buffer_;
   }
 
@@ -107,16 +107,16 @@ struct unsafe_access {
     @param storage instance of storage_adaptor.
   */
   template <class T>
-  static constexpr auto& storage_adaptor_impl(storage_adaptor<T>& storage) {
-    return static_cast<typename storage_adaptor<T>::impl_type&>(storage);
+  static constexpr auto& storage_adaptor_impl(T& storage) {
+    return static_cast<typename T::impl_type&>(storage);
   }
 
   /**
-    Get internal data of accumulators::mean.
+    Get internal data of accumulator.
     @param obj instance of accumulator.
   */
   template <class T>
-  static constexpr auto& accumulators_mean_impl(T& m) {
+  static constexpr auto& accumulator_data(T& m) {
     return m.data_;
   }
 };
diff --git a/test/accumulators_mean_test.cpp b/test/accumulators_mean_test.cpp
index 9ed185ec..46cd4759 100644
--- a/test/accumulators_mean_test.cpp
+++ b/test/accumulators_mean_test.cpp
@@ -118,7 +118,7 @@ int main() {
     a(2);
 
     BOOST_TEST_EQ(a.count(), 2);
-    unsafe_access::accumulators_mean_impl(a).sum_ = 1;
+    unsafe_access::accumulator_data(a).sum_ = 1;
     BOOST_TEST_EQ(a.count(), 1);
   }