Index: Misc/NEWS
===================================================================
--- Misc/NEWS	(revision 72434)
+++ Misc/NEWS	(working copy)
@@ -16,6 +16,14 @@
 -------
 
 
+Tests
+-----
+
+- Issue #5442: Make sure that case-senstivity tests are not run on OSs that are
+  *typically* on case-insensitive file systems but *can* be case-sensitive
+  (e.g. OS X on a UFS file system).
+
+
 What's New in Python 3.1 beta 1?
 ================================
 
Index: Lib/importlib/test/util.py
===================================================================
--- Lib/importlib/test/util.py	(revision 72434)
+++ Lib/importlib/test/util.py	(working copy)
@@ -10,11 +10,16 @@
     """Class decorator that nullifies tests that require a case-insensitive
     file system."""
     if sys.platform not in ('win32', 'darwin', 'cygwin'):
-        original_name = os.listdir('.')[0]
-        if original_name.upper() != original_name:
-            changed_name = original_name.upper()
+        for original_name in os.listdir('.'):
+            if original_name.upper() != original_name:
+                changed_name = original_name.upper()
+                break
+            elif original_name.lower() != original_name:
+                changed_name = original_name.lower()
+                break
         else:
-            changed_name = original_name.lower()
+            # No suitable path found to test against.
+            return unittest.TestCase
         if os.path.exists(changed_name):
             return class_
         return unittest.TestCase