diff -r a32a3b79f5e8 Misc/ACKS
--- a/Misc/ACKS	Sun May 12 17:29:34 2013 +0300
+++ b/Misc/ACKS	Tue May 14 16:13:49 2013 +0300
@@ -693,6 +693,7 @@
 Dom Mitchell
 Florian Mladitsch
 Doug Moen
+Jaakko Moisio
 The Dragon De Monsyne
 Skip Montanaro
 Paul Moore
diff -r a32a3b79f5e8 Objects/fileobject.c
--- a/Objects/fileobject.c	Sun May 12 17:29:34 2013 +0300
+++ b/Objects/fileobject.c	Tue May 14 16:13:49 2013 +0300
@@ -1802,7 +1802,7 @@
 {
     Py_buffer pbuf;
     const char *s;
-    Py_ssize_t n, n2;
+    Py_ssize_t n;
     PyObject *encoded = NULL;
 
     if (f->f_fp == NULL)
@@ -1848,12 +1848,12 @@
     f->f_softspace = 0;
     FILE_BEGIN_ALLOW_THREADS(f)
     errno = 0;
-    n2 = fwrite(s, 1, n, f->f_fp);
+    fwrite(s, 1, n, f->f_fp);
     FILE_END_ALLOW_THREADS(f)
     Py_XDECREF(encoded);
     if (f->f_binary)
         PyBuffer_Release(&pbuf);
-    if (n2 != n) {
+    if (ferror(f->f_fp)) {
         PyErr_SetFromErrno(PyExc_IOError);
         clearerr(f->f_fp);
         return NULL;