diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index 3c45032cda9138..0102f203340bd9 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -810,6 +810,12 @@ def __iter__(self):
 
 class TestSubclass(unittest.TestCase):
 
+    def test_copy_maxlen(self):
+        original = Deque('abc', maxlen=support.MAX_Py_ssize_t)
+        copied = original.copy()
+        self.assertEqual(copied, original)
+        self.assertEqual(copied.maxlen, original.maxlen)
+
     def test_basics(self):
         d = Deque(range(25))
         d.__init__(range(200))
diff --git a/Misc/NEWS.d/next/Library/2026-10-19-20-38-17.gh-issue-159739.ff088c.rst b/Misc/NEWS.d/next/Library/2026-10-19-20-38-17.gh-issue-159739.ff088c.rst
new file mode 100644
index 00000000000000..af8b06fecbfc3f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-10-19-20-38-17.gh-issue-159739.ff088c.rst
@@ -0,0 +1 @@
+Fix copying :class:`collections.deque` subclasses with a large maximum length.
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index e48fe39dda6a09..8e081f51afae93 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -645,7 +645,7 @@ deque_copy_impl(dequeobject *deque)
         result = PyObject_CallOneArg((PyObject *)(Py_TYPE(deque)),
                                      (PyObject *)deque);
     else
-        result = PyObject_CallFunction((PyObject *)(Py_TYPE(deque)), "Oi",
+        result = PyObject_CallFunction((PyObject *)(Py_TYPE(deque)), "On",
                                        deque, old_deque->maxlen, NULL);
     if (result != NULL && !PyObject_TypeCheck(result, state->deque_type)) {
         PyErr_Format(PyExc_TypeError,