diff --git a/Lib/posixpath.py b/Lib/posixpath.py
index 39b16a87c78..cb937963afd 100644
--- a/Lib/posixpath.py
+++ b/Lib/posixpath.py
@@ -71,7 +71,8 @@ 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."""
     sep = _get_sep(a)
     path = a
     try: