diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index d70f1dbf6..ae14a79df 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -4209,9 +4209,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 
         data() noexcept = default;
         data(data&&) noexcept = default;
-        data(const data&) noexcept = default;
-        data& operator=(data&&) noexcept = default;
-        data& operator=(const data&) noexcept = default;
+        data(const data&) noexcept = delete;
+        data& operator=(data&&) noexcept = delete;
+        data& operator=(const data&) noexcept = delete;
 
         ~data() noexcept
         {
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 326e6c275..d8cb8c97c 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -23425,9 +23425,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 
         data() noexcept = default;
         data(data&&) noexcept = default;
-        data(const data&) noexcept = default;
-        data& operator=(data&&) noexcept = default;
-        data& operator=(const data&) noexcept = default;
+        data(const data&) noexcept = delete;
+        data& operator=(data&&) noexcept = delete;
+        data& operator=(const data&) noexcept = delete;
 
         ~data() noexcept
         {