diff --git a/atmodriver.c b/atmodriver.c
index 237ccab..e54f254 100644
--- a/atmodriver.c
+++ b/atmodriver.c
@@ -539,7 +539,7 @@ static void atmo_driver_dealloc(py_atmo_driver_t *this)
   free_channels(ad);
   free_analyze_images(ad);
 
-  this->ob_type->tp_free((PyObject*)this);
+  Py_TYPE(this)->tp_free((PyObject*)this);
 }