Index: Include/unicodeobject.h
===================================================================
--- Include/unicodeobject.h	(revision 86944)
+++ Include/unicodeobject.h	(working copy)
@@ -1173,6 +1173,18 @@
     const char *errors          /* error handling */
     );
 
+/* Transforms code points that have decimal digit property to the
+   corresponding ASCII digit code points and transforms Unicode space to
+   '\N{SPACE}' (ASCII space).
+
+   Returns a new Unicode string on success, NULL on failure.
+*/
+
+PyAPI_FUNC(PyObject*) _PyUnicode_TransformDecimalToASCII(
+    Py_UNICODE *s,              /* Unicode buffer */
+    Py_ssize_t length           /* Number of Py_UNICODE chars to encode */
+    );
+
 /* --- File system encoding ---------------------------------------------- */
 
 /* ParseTuple converter: encode str objects to bytes using
Index: Objects/complexobject.c
===================================================================
--- Objects/complexobject.c	(revision 86944)
+++ Objects/complexobject.c	(working copy)
@@ -766,20 +766,17 @@
     char *end;
     double x=0.0, y=0.0, z;
     int got_bracket=0;
-    char *s_buffer = NULL;
+    PyObject *s_buffer = NULL;
     Py_ssize_t len;
 
     if (PyUnicode_Check(v)) {
-        s_buffer = (char *)PyMem_MALLOC(PyUnicode_GET_SIZE(v) + 1);
+        s_buffer = _PyUnicode_TransformDecimalToASCII(PyUnicode_AS_UNICODE(v),
+                                                      PyUnicode_GET_SIZE(v));
         if (s_buffer == NULL)
-            return PyErr_NoMemory();
-        if (PyUnicode_EncodeDecimal(PyUnicode_AS_UNICODE(v),
-                                    PyUnicode_GET_SIZE(v),
-                                    s_buffer,
-                                    NULL))
+            return NULL;
+        s = _PyUnicode_AsStringAndSize(s_buffer, &len);
+        if (s == NULL)
             goto error;
-        s = s_buffer;
-        len = strlen(s);
     }
     else if (PyObject_AsCharBuffer(v, &s, &len)) {
         PyErr_SetString(PyExc_TypeError,
@@ -894,16 +891,14 @@
     if (s-start != len)
         goto parse_error;
 
-    if (s_buffer)
-        PyMem_FREE(s_buffer);
+    Py_XDECREF(s_buffer);
     return complex_subtype_from_doubles(type, x, y);
 
   parse_error:
     PyErr_SetString(PyExc_ValueError,
                     "complex() arg is a malformed string");
   error:
-    if (s_buffer)
-        PyMem_FREE(s_buffer);
+    Py_XDECREF(s_buffer);
     return NULL;
 }
 
Index: Objects/unicodeobject.c
===================================================================
--- Objects/unicodeobject.c	(revision 86944)
+++ Objects/unicodeobject.c	(working copy)
@@ -6206,6 +6206,31 @@
     return NULL;
 }
 
+PyObject *
+_PyUnicode_TransformDecimalToASCII(Py_UNICODE *s,
+				   Py_ssize_t length)
+{
+    PyObject *result;
+    Py_UNICODE *p; /* write pointer into result */
+    Py_ssize_t i;
+    /* Copy to a new string */
+    result = PyUnicode_FromUnicode(s, length);
+    if (result == NULL)
+        return result;
+    p = PyUnicode_AS_UNICODE(result);
+    /* Iterate over code points */
+    for (i = 0; i < length; i++) {
+        Py_UNICODE ch =s[i];
+        if (ch != ' ' && Py_UNICODE_ISSPACE(ch))
+            p[i] = ' ';
+        else if (!Py_ISDIGIT(ch)) {
+            int decimal = Py_UNICODE_TODECIMAL(ch);
+            if (decimal >= 0)
+                p[i] = '0' + decimal;
+        }
+    }
+    return result;
+}
 /* --- Decimal Encoder ---------------------------------------------------- */
 
 int PyUnicode_EncodeDecimal(Py_UNICODE *s,
@@ -8985,6 +9010,13 @@
 }
 #endif
 
+static PyObject *
+unicode__decascii(PyObject *self)
+{
+    return _PyUnicode_TransformDecimalToASCII(PyUnicode_AS_UNICODE(self),
+					      PyUnicode_GET_SIZE(self));
+}
+
 PyDoc_STRVAR(startswith__doc__,
              "S.startswith(prefix[, start[, end]]) -> bool\n\
 \n\
@@ -9124,7 +9156,6 @@
     return Py_BuildValue("(u#)", v->str, v->length);
 }
 
-
 static PyMethodDef unicode_methods[] = {
 
     /* Order is according to common usage: often used methods should
@@ -9186,9 +9217,10 @@
 #endif
 
 #if 0
-    /* This one is just used for debugging the implementation. */
+    /* These methods are just used for debugging the implementation. */
     {"freelistsize", (PyCFunction) unicode_freelistsize, METH_NOARGS},
 #endif
+    {"_decascii", (PyCFunction) unicode__decascii, METH_NOARGS},
 
     {"__getnewargs__",  (PyCFunction)unicode_getnewargs, METH_NOARGS},
     {NULL, NULL}
Index: Objects/floatobject.c
===================================================================
--- Objects/floatobject.c	(revision 86944)
+++ Objects/floatobject.c	(working copy)
@@ -174,22 +174,21 @@
 {
     const char *s, *last, *end;
     double x;
-    char buffer[256]; /* for errors */
-    char *s_buffer = NULL;
+    PyObject *s_buffer = NULL;
     Py_ssize_t len;
     PyObject *result = NULL;
 
     if (PyUnicode_Check(v)) {
-        s_buffer = (char *)PyMem_MALLOC(PyUnicode_GET_SIZE(v)+1);
+        s_buffer = _PyUnicode_TransformDecimalToASCII(PyUnicode_AS_UNICODE(v),
+                                                      PyUnicode_GET_SIZE(v));
         if (s_buffer == NULL)
-            return PyErr_NoMemory();
-        if (PyUnicode_EncodeDecimal(PyUnicode_AS_UNICODE(v),
-                                    PyUnicode_GET_SIZE(v),
-                                    s_buffer,
-                                    NULL))
-            goto error;
-        s = s_buffer;
-        len = strlen(s);
+            return NULL;
+        s = _PyUnicode_AsStringAndSize(s_buffer, &len);
+        if (s == NULL) {
+            Py_DECREF(s_buffer);
+            return NULL;
+        }
+        last = s + len;
     }
     else if (PyObject_AsCharBuffer(v, &s, &len)) {
         PyErr_SetString(PyExc_TypeError,
@@ -197,29 +196,27 @@
         return NULL;
     }
     last = s + len;
-
-    while (Py_ISSPACE(*s))
+    /* strip space */
+    while (s < last && Py_ISSPACE(*s))
         s++;
+    while (s < last - 1 && Py_ISSPACE(last[-1]))
+        last--;
     /* We don't care about overflow or underflow.  If the platform
      * supports them, infinities and signed zeroes (on underflow) are
      * fine. */
     x = PyOS_string_to_double(s, (char **)&end, NULL);
-    if (x == -1.0 && PyErr_Occurred())
-        goto error;
-    while (Py_ISSPACE(*end))
-        end++;
-    if (end == last)
-        result = PyFloat_FromDouble(x);
-    else {
-        PyOS_snprintf(buffer, sizeof(buffer),
-                      "invalid literal for float(): %.200s", s);
-        PyErr_SetString(PyExc_ValueError, buffer);
+    if (end != last) {
+        PyErr_Format(PyExc_ValueError,
+                     "could not convert string to float: "
+                     "%.200s", s);
         result = NULL;
     }
+    else if (x == -1.0 && PyErr_Occurred())
+        result = NULL;
+    else
+        result = PyFloat_FromDouble(x);
 
-  error:
-    if (s_buffer)
-        PyMem_FREE(s_buffer);
+    Py_XDECREF(s_buffer);
     return result;
 }
 
Index: Lib/test/test_float.py
===================================================================
--- Lib/test/test_float.py	(revision 86944)
+++ Lib/test/test_float.py	(working copy)
@@ -51,6 +51,17 @@
         float(b'.' + b'1'*1000)
         float('.' + '1'*1000)
 
+    def test_error_message(self):
+        testlist = ('\xbd', '123\xbd', '  123 456  ')
+        for s in testlist:
+            try:
+                float(s)
+            except ValueError as e:
+                self.assertIn(s.strip(), e.args[0])
+            else:
+                self.fail("Expected int(%r) to raise a ValueError", s)
+
+
     @support.run_with_locale('LC_NUMERIC', 'fr_FR', 'de_DE')
     def test_float_with_comma(self):
         # set locale to something that doesn't use '.' for the decimal point