diff --git a/mercury.c b/mercury.c
index 1e7bc666..ff652445 100644
--- a/mercury.c
+++ b/mercury.c
@@ -2236,6 +2236,7 @@ static PyTypeObject TagReadDataType = {
 static void
 ReaderStatsData_dealloc(ReaderStatsData* self)
 {
+    Py_XDECREF(self->protocol);
     Py_TYPE(self)->tp_free((PyObject*)self);
 };