diff --git a/Objects/longobject.c b/Objects/longobject.c
index 4d886cd..cb4900d 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -3287,8 +3287,25 @@
 		return PyLong_FromLong(0L);
 	if (base == -909)
 		return PyNumber_Long(x);
-	else if (PyString_Check(x))
+	else if (PyString_Check(x)) {
+		/* Since PyLong_FromString doesn't have a length parameter,
+		 * check here for possible NULs in the string. */
+		char *string = PyString_AS_STRING(x);
+		if (strlen(string) != PyString_Size(x)) {
+			/* create a repr() of the input string,
+			 * just like PyLong_FromString does. */
+			PyObject *srepr;
+			srepr = PyObject_Repr(x);
+			if (srepr == NULL)
+				return NULL;
+			PyErr_Format(PyExc_ValueError,
+			     "invalid literal for long() with base %d: %s",
+			     base, PyString_AS_STRING(srepr));
+			Py_DECREF(srepr);
+			return NULL;
+		}
 		return PyLong_FromString(PyString_AS_STRING(x), NULL, base);
+	}
 #ifdef Py_USING_UNICODE
 	else if (PyUnicode_Check(x))
 		return PyLong_FromUnicode(PyUnicode_AS_UNICODE(x),