diff --git a/Lib/posixfile.py b/Lib/posixfile.py
index dcd65cd..e2eb024 100644
--- a/Lib/posixfile.py
+++ b/Lib/posixfile.py
@@ -53,6 +53,13 @@
               query only
 """
 
+import warnings
+warnings.warn(
+    "The posixfile module is obsolete and will disappear in the future",
+    DeprecationWarning)
+del warnings
+
+
 class _posixfile_:
     """File wrapper class that provides extra POSIX file routines."""