diff --git a/testing/util.py b/testing/util.py
index 43014df4..6a66c7c9 100644
--- a/testing/util.py
+++ b/testing/util.py
@@ -48,7 +48,16 @@ xfailif_windows_no_ruby = pytest.mark.xfail(
 def broken_deep_listdir():  # pragma: no cover (platform specific)
     if sys.platform != 'win32':
         return False
-    return True  # see #798
+    try:
+        os.listdir(str('\\\\?\\') + os.path.abspath(str('.')))
+    except OSError:
+        return True
+    try:
+        os.listdir(b'\\\\?\\C:' + b'\\' * 300)
+    except TypeError:
+        return True
+    except OSError:
+        return False
 
 
 xfailif_broken_deep_listdir = pytest.mark.xfail(