diff --git a/arch/univariate/base.py b/arch/univariate/base.py
index 3e87980556..2db509e068 100644
--- a/arch/univariate/base.py
+++ b/arch/univariate/base.py
@@ -27,7 +27,7 @@
                                      data_scale_warning,
                                      starting_value_warning)
 from arch.utility.testing import WaldTestStatistic
-from property_cached import cached_property
+from arch.vendor import cached_property
 
 __all__ = ['implicit_constant', 'ARCHModelResult', 'ARCHModel', 'ARCHModelForecast', 'constraint']
 
diff --git a/arch/univariate/mean.py b/arch/univariate/mean.py
index 56fb21e72a..ca2e544b92 100644
--- a/arch/univariate/mean.py
+++ b/arch/univariate/mean.py
@@ -19,7 +19,7 @@
 from arch.univariate.volatility import (ARCH, EGARCH, FIGARCH, GARCH, HARCH,
                                         ConstantVariance)
 from arch.utility.array import cutoff_to_index, ensure1d, parse_dataframe
-from property_cached import cached_property
+from arch.vendor import cached_property
 
 __all__ = ['HARX', 'ConstantMean', 'ZeroMean', 'ARX', 'arch_model', 'LS']
 
diff --git a/arch/utility/array.py b/arch/utility/array.py
index e63d12c8be..f9a67c6da3 100644
--- a/arch/utility/array.py
+++ b/arch/utility/array.py
@@ -8,12 +8,12 @@
 from abc import ABCMeta
 import datetime as dt
 
-from property_cached import cached_property
-
 import numpy as np
 from pandas import (DataFrame, DatetimeIndex, NaT, Series, Timestamp,
                     to_datetime)
 
+from arch.vendor import cached_property
+
 __all__ = ['ensure1d', 'parse_dataframe', 'DocStringInheritor',
            'date_to_index', 'cutoff_to_index', 'ensure2d', 'AbstractDocStringInheritor']
 
diff --git a/arch/utility/testing.py b/arch/utility/testing.py
index f4a7b0082f..3b347c0f10 100644
--- a/arch/utility/testing.py
+++ b/arch/utility/testing.py
@@ -4,7 +4,7 @@
 
 from scipy.stats import chi2
 
-from property_cached import cached_property
+from arch.vendor import cached_property
 
 __all__ = ['WaldTestStatistic']
 
diff --git a/arch/vendor/property_cached.py b/arch/vendor/property_cached.py
index ff7c1d40cc..b2f3899e24 100644
--- a/arch/vendor/property_cached.py
+++ b/arch/vendor/property_cached.py
@@ -33,8 +33,8 @@
 import functools
 import sys
 import threading
-import weakref
 from time import time
+import weakref
 
 try:
     import asyncio