Index: Python/compile.c
===================================================================
--- Python/compile.c	(revision 74170)
+++ Python/compile.c	(working copy)
@@ -3943,7 +3943,7 @@
 	freevars = dict_keys_inorder(c->u->u_freevars, PyTuple_Size(cellvars));
 	if (!freevars)
 	    goto error;
-	filename = PyUnicode_DecodeFSDefault(c->c_filename);
+	filename = PyUnicode_FromString(c->c_filename);
 	if (!filename)
 		goto error;
 
Index: Python/pythonrun.c
===================================================================
--- Python/pythonrun.c	(revision 74170)
+++ Python/pythonrun.c	(working copy)
@@ -1153,7 +1153,7 @@
 	d = PyModule_GetDict(m);
 	if (PyDict_GetItemString(d, "__file__") == NULL) {
 		PyObject *f;
-		f = PyUnicode_DecodeFSDefault(filename);
+		f = PyUnicode_FromString(filename);
 		if (f == NULL)
 			return -1;
 		if (PyDict_SetItemString(d, "__file__", f) < 0) {
Index: Python/traceback.c
===================================================================
--- Python/traceback.c	(revision 74170)
+++ Python/traceback.c	(working copy)
@@ -133,33 +133,34 @@
 	return 0;
 }
 
-static int
-_Py_FindSourceFile(const char* filename, char* namebuf, size_t namelen, int open_flags)
+static PyObject *
+_Py_FindSourceFile(PyObject *filename, char* namebuf, size_t namelen, PyObject *io)
 {
-	int i;
-	int fd = -1;
+	Py_ssize_t i;
+	PyObject *binary;
 	PyObject *v;
-	Py_ssize_t _npath;
-	int npath;
+	Py_ssize_t npath;
 	size_t taillen;
 	PyObject *syspath;
 	const char* path;
 	const char* tail;
+	const char* filepath;
 	Py_ssize_t len;
 
+	filepath = _PyUnicode_AsString(filename);
+
 	/* Search tail of filename in sys.path before giving up */
-	tail = strrchr(filename, SEP);
+	tail = strrchr(filepath, SEP);
 	if (tail == NULL)
-		tail = filename;
+		tail = filepath;
 	else
 		tail++;
 	taillen = strlen(tail);
 
 	syspath = PySys_GetObject("path");
 	if (syspath == NULL || !PyList_Check(syspath))
-		return -1;
-	_npath = PyList_Size(syspath);
-	npath = Py_SAFE_DOWNCAST(_npath, Py_ssize_t, int);
+		return NULL;
+	npath = PyList_Size(syspath);
 
 	for (i = 0; i < npath; i++) {
 		v = PyList_GetItem(syspath, i);
@@ -178,31 +179,28 @@
 		if (len > 0 && namebuf[len-1] != SEP)
 			namebuf[len++] = SEP;
 		strcpy(namebuf+len, tail);
-		Py_BEGIN_ALLOW_THREADS
-		fd = open(namebuf, open_flags);
-		Py_END_ALLOW_THREADS
-		if (0 <= fd) {
-			return fd;
+
+		binary = PyObject_CallMethod(io, "open", "ss", namebuf, "rb");
+		if (binary != NULL) {
+			return NULL;
 		}
+		PyErr_Clear();
 	}
-	return -1;
+	return NULL;
 }
 
 int
-_Py_DisplaySourceLine(PyObject *f, const char *filename, int lineno, int indent)
+_Py_DisplaySourceLine(PyObject *f, PyObject *filename, int lineno, int indent)
 {
 	int err = 0;
 	int fd;
 	int i;
 	char *found_encoding;
 	char *encoding;
+	PyObject *io;
+	PyObject *binary;
 	PyObject *fob = NULL;
 	PyObject *lineobj = NULL;
-#ifdef O_BINARY
-	const int open_flags = O_RDONLY | O_BINARY;   /* necessary for Windows */
-#else
-	const int open_flags = O_RDONLY;
-#endif
 	char buf[MAXPATHLEN+1];
 	Py_UNICODE *u, *p;
 	Py_ssize_t len;
@@ -210,27 +208,33 @@
 	/* open the file */
 	if (filename == NULL)
 		return 0;
-	Py_BEGIN_ALLOW_THREADS
-	fd = open(filename, open_flags);
-	Py_END_ALLOW_THREADS
-	if (fd < 0) {
-		fd = _Py_FindSourceFile(filename, buf, sizeof(buf), open_flags);
-		if (fd < 0)
+
+	io = PyImport_ImportModuleNoBlock("io");
+	if (io == NULL)
+		return -1;
+	binary = PyObject_CallMethod(io, "open", "Os", filename, "rb");
+
+	if (binary == NULL) {
+		binary = _Py_FindSourceFile(filename, buf, sizeof(buf), io);
+		if (binary == NULL) {
+			Py_DECREF(io);
 			return 0;
-		filename = buf;
+		}
 	}
 
 	/* use the right encoding to decode the file as unicode */
+	fd = PyObject_AsFileDescriptor(binary);
 	found_encoding = PyTokenizer_FindEncoding(fd);
 	encoding = (found_encoding != NULL) ? found_encoding :
 		(char*)PyUnicode_GetDefaultEncoding();
 	lseek(fd, 0, 0); /* Reset position */
-	fob = PyFile_FromFd(fd, (char*)filename, "r", -1, (char*)encoding,
-		NULL, NULL, 1);
+	fob = PyObject_CallMethod(io, "TextIOWrapper", "Os", binary, encoding);
+	Py_DECREF(io);
+	Py_DECREF(binary);
 	PyMem_FREE(found_encoding);
+
 	if (fob == NULL) {
 		PyErr_Clear();
-		close(fd);
 		return 0;
 	}
 
@@ -287,7 +291,7 @@
 }
 
 static int
-tb_displayline(PyObject *f, const char *filename, int lineno, const char *name)
+tb_displayline(PyObject *f, PyObject *filename, int lineno, const char *name)
 {
 	int err = 0;
         char linebuf[2000];
@@ -296,7 +300,8 @@
 		return -1;
 	/* This is needed by Emacs' compile command */
 #define FMT "  File \"%.500s\", line %d, in %.500s\n"
-	PyOS_snprintf(linebuf, sizeof(linebuf), FMT, filename, lineno, name);
+	PyOS_snprintf(linebuf, sizeof(linebuf), FMT,
+	    _PyUnicode_AsString(filename), lineno, name);
 	err = PyFile_WriteString(linebuf, f);
 	if (err != 0)
 		return err;
@@ -316,8 +321,7 @@
 	while (tb != NULL && err == 0) {
 		if (depth <= limit) {
 			err = tb_displayline(f,
-			    _PyUnicode_AsString(
-				    tb->tb_frame->f_code->co_filename),
+			    tb->tb_frame->f_code->co_filename,
 			    tb->tb_lineno,
 			    _PyUnicode_AsString(tb->tb_frame->f_code->co_name));
 		}
Index: Python/_warnings.c
===================================================================
--- Python/_warnings.c	(revision 74170)
+++ Python/_warnings.c	(working copy)
@@ -282,8 +282,7 @@
         PyFile_WriteString("\n", f_stderr);
     }
     else
-        if (_Py_DisplaySourceLine(f_stderr, _PyUnicode_AsString(filename),
-                              lineno, 2) < 0)
+        if (_Py_DisplaySourceLine(f_stderr, filename, lineno, 2) < 0)
 		return;
     PyErr_Clear();
 }
Index: Include/traceback.h
===================================================================
--- Include/traceback.h	(revision 74170)
+++ Include/traceback.h	(working copy)
@@ -19,7 +19,7 @@
 
 PyAPI_FUNC(int) PyTraceBack_Here(struct _frame *);
 PyAPI_FUNC(int) PyTraceBack_Print(PyObject *, PyObject *);
-PyAPI_FUNC(int) _Py_DisplaySourceLine(PyObject *, const char *, int, int);
+PyAPI_FUNC(int) _Py_DisplaySourceLine(PyObject *, PyObject *, int, int);
 
 /* Reveal traceback type so we can typecheck traceback objects */
 PyAPI_DATA(PyTypeObject) PyTraceBack_Type;