diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index b94f502f8..6bf77d507 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -1872,7 +1872,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template < typename ValueType, typename std::enable_if <
                    detail::conjunction <
                        detail::negation<std::is_pointer<ValueType>>,
-                       detail::negation<std::is_same<ValueType, nullptr_t>>,
+                       detail::negation<std::is_same<ValueType, std::nullptr_t>>,
                        detail::negation<std::is_same<ValueType, detail::json_ref<basic_json>>>,
                                         detail::negation<std::is_same<ValueType, typename string_t::value_type>>,
                                         detail::negation<detail::is_basic_json<ValueType>>,
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 8fd2b357f..8e882b3ad 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -19043,7 +19043,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     template < typename ValueType, typename std::enable_if <
                    detail::conjunction <
                        detail::negation<std::is_pointer<ValueType>>,
-                       detail::negation<std::is_same<ValueType, nullptr_t>>,
+                       detail::negation<std::is_same<ValueType, std::nullptr_t>>,
                        detail::negation<std::is_same<ValueType, detail::json_ref<basic_json>>>,
                                         detail::negation<std::is_same<ValueType, typename string_t::value_type>>,
                                         detail::negation<detail::is_basic_json<ValueType>>,