diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index 7896143..70f787f 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -2073,6 +2073,11 @@
 static PyObject *
 count_next(countobject *lz)
 {
+        if (lz->cnt == LONG_MAX) {
+                PyErr_SetString(PyExc_OverflowError,
+                        "cannot count beyond LONG_MAX");                
+                return NULL;         
+        }
 	return PyInt_FromSsize_t(lz->cnt++);
 }