diff --git a/Lib/posixpath.py b/Lib/posixpath.py
index 1c63af8..7f907ef 100644
--- a/Lib/posixpath.py
+++ b/Lib/posixpath.py
@@ -303,11 +303,11 @@
     do nothing."""
     if not path.startswith('~'):
         return path
-    i, n = 1, len(path)
-    while i < n and path[i] != '/':
-        i += 1
+    i = path.find('/', 1)
+    if i < 0:
+        i = len(path)
     if i == 1:
-        if not 'HOME' in os.environ:
+        if 'HOME' not in os.environ:
             import pwd
             userhome = pwd.getpwuid(os.getuid()).pw_dir
         else:
diff --git a/Lib/test/test_posixpath.py b/Lib/test/test_posixpath.py
index 9ba7216..30551d8 100644
--- a/Lib/test/test_posixpath.py
+++ b/Lib/test/test_posixpath.py
@@ -332,12 +332,16 @@
 
     def test_expanduser(self):
         self.assertEqual(posixpath.expanduser("foo"), "foo")
-        self.assert_(isinstance(posixpath.expanduser("~/"), basestring))
         try:
             import pwd
         except ImportError:
             pass
         else:
+            self.assert_(isinstance(posixpath.expanduser("~/"), basestring))
+            self.assertEqual(
+                posixpath.expanduser("~") + "/",
+                posixpath.expanduser("~/")
+            )
             self.assert_(isinstance(posixpath.expanduser("~root/"), basestring))
             self.assert_(isinstance(posixpath.expanduser("~foo/"), basestring))