diff -r d8e49a2795e7 Modules/_io/fileio.c
--- a/Modules/_io/fileio.c	Sat Mar 07 18:14:07 2015 -0800
+++ b/Modules/_io/fileio.c	Sun Mar 08 03:26:51 2015 +0100
@@ -182,13 +182,7 @@ check_fd(int fd)
 {
 #if defined(HAVE_FSTAT) || defined(MS_WINDOWS)
     struct _Py_stat_struct buf;
-    if (_Py_fstat(fd, &buf) < 0 &&
-#ifdef MS_WINDOWS
-        GetLastError() == ERROR_INVALID_HANDLE
-#else
-        errno == EBADF
-#endif
-        ) {
+    if (_Py_fstat(fd, &buf) < 0 && errno == EBADF) {
         PyObject *exc;
         char *msg = strerror(EBADF);
         exc = PyObject_CallFunction(PyExc_OSError, "(is)",
diff -r d8e49a2795e7 Modules/signalmodule.c
--- a/Modules/signalmodule.c	Sat Mar 07 18:14:07 2015 -0800
+++ b/Modules/signalmodule.c	Sun Mar 08 03:26:51 2015 +0100
@@ -560,7 +560,7 @@ signal_set_wakeup_fd(PyObject *self, PyO
             }
 
             if (_Py_fstat(fd, &st) != 0) {
-                PyErr_SetExcFromWindowsErr(PyExc_OSError, GetLastError());
+                PyErr_SetFromErrno(PyExc_OSError);
                 return NULL;
             }
 
diff -r d8e49a2795e7 Python/fileutils.c
--- a/Python/fileutils.c	Sat Mar 07 18:14:07 2015 -0800
+++ b/Python/fileutils.c	Sun Mar 08 03:26:51 2015 +0100
@@ -637,14 +637,11 @@ int
     else
         h = (HANDLE)_get_osfhandle(fd);
 
-    /* Protocol violation: we explicitly clear errno, instead of
-       setting it to a POSIX error. Callers should use GetLastError. */
     errno = 0;
 
     if (h == INVALID_HANDLE_VALUE) {
-        /* This is really a C library error (invalid file handle).
-           We set the Win32 error to the closes one matching. */
         SetLastError(ERROR_INVALID_HANDLE);
+        errno = EBADF;
         return -1;
     }
     memset(result, 0, sizeof(*result));
@@ -653,6 +650,7 @@ int
     if (type == FILE_TYPE_UNKNOWN) {
         DWORD error = GetLastError();
         if (error != 0) {
+            errno = winerror_to_errno(error);
             return -1;
         }
         /* else: valid but unknown file */
@@ -667,6 +665,7 @@ int
     }
 
     if (!GetFileInformationByHandle(h, &info)) {
+        errno = winerror_to_errno(error);
         return -1;
     }