diff --git a/include/nlohmann/byte_container_with_subtype.hpp b/include/nlohmann/byte_container_with_subtype.hpp
index b9a1faf3e..ffbacdc6d 100644
--- a/include/nlohmann/byte_container_with_subtype.hpp
+++ b/include/nlohmann/byte_container_with_subtype.hpp
@@ -27,7 +27,7 @@ class byte_container_with_subtype : public BinaryType
     /// the type of the underlying container
     using container_type = BinaryType;
     /// the type of the subtype
-    using subtype_type = std::uint8_t;
+    using subtype_type = std::uint64_t;
 
     byte_container_with_subtype() noexcept(noexcept(container_type()))
         : container_type()
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 6efa460ee..3fcf708b1 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -4983,7 +4983,7 @@ class byte_container_with_subtype : public BinaryType
     /// the type of the underlying container
     using container_type = BinaryType;
     /// the type of the subtype
-    using subtype_type = std::uint8_t;
+    using subtype_type = std::uint64_t;
 
     byte_container_with_subtype() noexcept(noexcept(container_type()))
         : container_type()