diff --git a/Doc/lib/libtarfile.tex b/Doc/lib/libtarfile.tex
index c841123..ce07c3e 100644
--- a/Doc/lib/libtarfile.tex
+++ b/Doc/lib/libtarfile.tex
@@ -261,7 +261,8 @@
     gigabytes. A \exception{ValueError} is raised if a file exceeds
     this limit.  If false, create a GNU tar compatible archive.  It
     will not be \POSIX{} compliant, but can store files without any
-    of the above restrictions.
+    of the above restrictions. 
+    \versionchanged[\var{posix} defaults to false.]{2.4}
 \end{memberdesc}
 
 \begin{memberdesc}{dereference}
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 64d006d..ba5a1d2 100644
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -781,7 +781,7 @@
                                 # messages (if debug >= 0). If > 0, errors
                                 # are passed to the caller as exceptions.
 
-    posix = True                # If True, generates POSIX.1-1990-compliant
+    posix = False               # If True, generates POSIX.1-1990-compliant
                                 # archives (no GNU extensions!)
 
     fileobject = ExFileObject
@@ -1137,7 +1137,7 @@
         tarinfo.mode  = stmd
         tarinfo.uid   = statres.st_uid
         tarinfo.gid   = statres.st_gid
-        tarinfo.size  = statres.st_size
+        tarinfo.size  = not stat.S_ISDIR(stmd) and statres.st_size or 0
         tarinfo.mtime = statres.st_mtime
         tarinfo.type  = type
         tarinfo.linkname = linkname
diff --git a/Misc/NEWS b/Misc/NEWS
index c6857dc..184c15c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -44,6 +44,8 @@
 Library
 -------
 
+- tarfile now generates GNU tar files by default.
+
 - HTTPResponse has now a getheaders method.
 
 - Patch #1006219: let inspect.getsource handle '@' decorators. Thanks Simon