diff --git a/include/nlohmann/detail/hash.hpp b/include/nlohmann/detail/hash.hpp
index 70c5daf338..ac07c2e8f0 100644
--- a/include/nlohmann/detail/hash.hpp
+++ b/include/nlohmann/detail/hash.hpp
@@ -103,7 +103,7 @@ std::size_t hash(const BasicJsonType& j)
             auto seed = combine(type, j.get_binary().size());
             const auto h = std::hash<bool> {}(j.get_binary().has_subtype());
             seed = combine(seed, h);
-            seed = combine(seed, j.get_binary().subtype());
+            seed = combine(seed, static_cast<std::size_t>(j.get_binary().subtype()));
             for (const auto byte : j.get_binary())
             {
                 seed = combine(seed, std::hash<std::uint8_t> {}(byte));
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 5f810e291e..16afb8a6a7 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -5266,7 +5266,7 @@ std::size_t hash(const BasicJsonType& j)
             auto seed = combine(type, j.get_binary().size());
             const auto h = std::hash<bool> {}(j.get_binary().has_subtype());
             seed = combine(seed, h);
-            seed = combine(seed, j.get_binary().subtype());
+            seed = combine(seed, static_cast<std::size_t>(j.get_binary().subtype()));
             for (const auto byte : j.get_binary())
             {
                 seed = combine(seed, std::hash<std::uint8_t> {}(byte));