diff --git a/Lib/posixpath.py b/Lib/posixpath.py
index 690c70da374..5ddf25b1067 100644
--- a/Lib/posixpath.py
+++ b/Lib/posixpath.py
@@ -68,7 +68,8 @@ def isabs(s):
 def join(a, *p):
     """Join two or more pathname components, inserting '/' as needed.
     If any component is an absolute path, all previous path components
-    will be discarded."""
+    will be discarded.  An empty last part will result in a path that
+    ends with a separator."""
     path = a
     for b in p:
         if b.startswith('/'):