diff --git a/include/pybind11/pytypes.h b/include/pybind11/pytypes.h
index ab6cc3473..8678d7003 100644
--- a/include/pybind11/pytypes.h
+++ b/include/pybind11/pytypes.h
@@ -449,7 +449,7 @@ public:
 
 private:
     mutable std::string m_lazy_what;
-    mutable object m_type, m_value, m_trace;
+    object m_type, m_value, m_trace;
 };
 #if defined(_MSC_VER)
 #    pragma warning(pop)