diff --git a/Lib/stat.py b/Lib/stat.py
index afb9a050581..381e28a9bcf 100644
--- a/Lib/stat.py
+++ b/Lib/stat.py
@@ -29,7 +29,7 @@ def S_IMODE(mode):
 	return mode & 07777
 
 def S_IFMT(mode):
-	return mode & ~07777
+	return mode & 0170000
 
 # Constants used as S_IFMT() for various file types
 # (not all are implemented on all systems)
@@ -64,3 +64,25 @@ def S_ISLNK(mode):
 
 def S_ISSOCK(mode):
 	return S_IFMT(mode) == S_IFSOCK
+
+# Names for permission bits
+
+S_ISUID = 04000
+S_ISGID = 02000
+S_ENFMT = S_ISGID
+S_ISVTX = 01000
+S_IREAD = 00400
+S_IWRITE = 00200
+S_IEXEC = 00100
+S_IRWXU = 00700
+S_IRUSR = 00400
+S_IWUSR = 00200
+S_IXUSR = 00100
+S_IRWXG = 00070
+S_IRGRP = 00040
+S_IWGRP = 00020
+S_IXGRP = 00010
+S_IRWXO = 00007
+S_IROTH = 00004
+S_IWOTH = 00002
+S_IXOTH = 00001