1 files changed, 8 insertions, 3 deletions
diff --git a/Objects/iterobject.c b/Objects/iterobject.c
index 3cfbeaf..9acd1b7 100644
--- a/Objects/iterobject.c
+++ b/Objects/iterobject.c
@@ -76,9 +76,14 @@ iter_len(seqiterobject *it)
     Py_ssize_t seqsize, len;
 
     if (it->it_seq) {
-        seqsize = PySequence_Size(it->it_seq);
-        if (seqsize == -1)
-            return NULL;
+        if (_PyObject_HasLen(it->it_seq)) {
+            seqsize = PySequence_Size(it->it_seq);
+            if (seqsize == -1)
+                return NULL;
+        }
+        else {
+            Py_RETURN_NOTIMPLEMENTED;
+        }
         len = seqsize - it->it_index;
         if (len >= 0)
             return PyLong_FromSsize_t(len);