diff --git a/test_zipp.py b/test_zipp.py
index 3c4bef0..b6ef0f6 100644
--- a/test_zipp.py
+++ b/test_zipp.py
@@ -4,7 +4,6 @@
 
 import io
 import zipfile
-import posixpath
 import contextlib
 import pathlib
 import unittest
@@ -109,6 +108,14 @@ def test_iterdir_and_types(self):
             i, = h.iterdir()
             assert i.is_file()
 
+    def test_subdir_is_dir(self):
+        for alpharep in self.zipfile_alpharep():
+            root = zipp.Path(alpharep)
+            assert (root / 'b').is_dir()
+            assert (root / 'b/').is_dir()
+            assert (root / 'g').is_dir()
+            assert (root / 'g/').is_dir()
+
     def test_open(self):
         for alpharep in self.zipfile_alpharep():
             root = zipp.Path(alpharep)