diff --git a/NEWS b/NEWS
index 28a9ac2f..ced7230c 100644
--- a/NEWS
+++ b/NEWS
@@ -37,6 +37,7 @@ What's new in psycopg 2.6.2
 - Fix build on Windows with Python 3.5, VS 2015 (:ticket:`#380`).
 - Fixed `!errorcodes.lookup` initialization thread-safety (:ticket:`#382`).
 - Fixed `!read()` exception propagation in copy_from (:ticket:`#412`).
+- Fixed possible NULL TZ decref  (:ticket:`#424`).
 
 
 What's new in psycopg 2.6.1
diff --git a/psycopg/adapter_datetime.c b/psycopg/adapter_datetime.c
index 0571837d..9d04df40 100644
--- a/psycopg/adapter_datetime.c
+++ b/psycopg/adapter_datetime.c
@@ -451,7 +451,7 @@ psyco_TimestampFromTicks(PyObject *self, PyObject *args)
         tz);
 
 exit:
-    Py_DECREF(tz);
+    Py_XDECREF(tz);
     Py_XDECREF(m);
     return res;
 }