diff --git a/include/json/value.h b/include/json/value.h
index dffc51a..df1eba6 100644
--- a/include/json/value.h
+++ b/include/json/value.h
@@ -342,6 +342,7 @@ public:
   Value(const StaticString& value);
   Value(const String& value);
   Value(bool value);
+  Value(std::nullptr_t ptr) = delete;
   Value(const Value& other);
   Value(Value&& other);
   ~Value();