diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index ce05b6e4e6..e828f725dd 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -312,6 +312,10 @@ class cpp_function : public function {
     // along the way.
     class strdup_guard {
     public:
+        strdup_guard() = default;
+        strdup_guard(const strdup_guard &) = delete;
+        strdup_guard &operator=(const strdup_guard &) = delete;
+
         ~strdup_guard() {
             for (auto *s : strings) {
                 std::free(s);