diff --git a/pydocx/util/memoize.py b/pydocx/util/memoize.py
index c9868b73..1af18f89 100644
--- a/pydocx/util/memoize.py
+++ b/pydocx/util/memoize.py
@@ -21,7 +21,7 @@ def __init__(self, func):
         self.cache = {}
 
     def __call__(self, *args):
-        if not isinstance(args, collections.Hashable):
+        if not isinstance(args, collections.abc.Hashable):
             # uncacheable. a list, for instance.
             # better to not cache than blow up.
             return self.func(*args)