diff --git a/ChangeLog b/ChangeLog
index 48f3677..b17d291 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2022.09.28, Version 0.0.21
+
+  * Use build-in function.
+
 2022.09.28, Version 0.0.20
 
   * Added `use_tuples` unpack argument (pr #5).
diff --git a/qpack/__init__.py b/qpack/__init__.py
index 533a51a..d9841d5 100644
--- a/qpack/__init__.py
+++ b/qpack/__init__.py
@@ -11,6 +11,6 @@
 except ImportError as ex:
     from .fallback import packb, unpackb
 
-__version_info__ = (0, 0, 20)
+__version_info__ = (0, 0, 21)
 __version__ = '.'.join(map(str, __version_info__))
 __all__ = ['packb', 'unpackb']
diff --git a/qpack/_qpack.c b/qpack/_qpack.c
index 431af49..f2fe21a 100644
--- a/qpack/_qpack.c
+++ b/qpack/_qpack.c
@@ -1112,19 +1112,9 @@ static PyObject * unpackb(
             }
             if (options->use_tuples)
             {
-                Py_ssize_t i, size = PyList_Size(obj);
-                o = PyTuple_New(size);
-                if (o != NULL)
-                {
-                    for (i = 0; i < size; i++)
-                    {
-                        PyObject * v = PyList_GetItem(obj, i);
-                        Py_INCREF(v);
-                        PyTuple_SET_ITEM(o, i, v);
-                    }
-                    Py_DECREF(obj);
-                    return o;
-                }
+                o = PyList_AsTuple(obj);
+                Py_DECREF(obj);
+                return o;
             }
             return obj;
         }