diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index 859abf0..8ef3261 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -1073,6 +1073,163 @@
 	return v;
 }
 
+static PyObject *
+float_as_integer_ratio(PyObject *v)
+{
+	double self;
+	double float_part;
+	int exponent;
+	int is_negative;
+	const int chunk_size = 28;
+	PyObject *prev;
+	PyObject *py_chunk = NULL;
+	PyObject *py_exponent = NULL;
+	PyObject *numerator = NULL;
+	PyObject *denominator = NULL;
+	PyObject *result_pair = NULL;
+	PyNumberMethods *long_methods;
+
+#define INPLACE_UPDATE(obj, call) \
+	prev = obj; \
+	obj = call; \
+	Py_DECREF(prev); \
+
+	CONVERT_TO_DOUBLE(v, self);
+
+	if (Py_IS_INFINITY(self)) {
+	  PyErr_SetString(PyExc_OverflowError,
+			  "Cannot pass infinity to float.as_integer_ratio.");
+	  return NULL;
+	}
+#ifdef Py_NAN
+	if (Py_IS_NAN(self)) {
+	  PyErr_SetString(PyExc_ValueError,
+			  "Cannot pass nan to float.as_integer_ratio.");
+	  return NULL;
+	}
+#endif
+
+	if (self == 0) {
+		numerator = PyLong_FromLong(0);
+		if (numerator == NULL) goto error;
+		denominator = PyLong_FromLong(1);
+		if (denominator == NULL) goto error;
+		result_pair = PyTuple_Pack(2, numerator, denominator);
+		/* Hand ownership over to the tuple. If the tuple
+		   wasn't created successfully, we want to delete the
+		   ints anyway. */
+		Py_DECREF(numerator);
+		Py_DECREF(denominator);
+		return result_pair;
+	}
+
+	/* XXX: Could perhaps handle FLT_RADIX!=2 by using ilogb and
+	   scalbn, but those may not be in C89. */
+	PyFPE_START_PROTECT("as_integer_ratio", goto error);
+	float_part = frexp(self, &exponent);
+	is_negative = 0;
+	if (float_part < 0) {
+		float_part = -float_part;
+		is_negative = 1;
+		/* 0.5 <= float_part < 1.0 */
+	}
+	PyFPE_END_PROTECT(float_part);
+	/* abs(self) == float_part * 2**exponent exactly */
+
+	/* Suck up chunk_size bits at a time; 28 is enough so that we
+	   suck up all bits in 2 iterations for all known binary
+	   double-precision formats, and small enough to fit in a
+	   long. */
+	numerator = PyLong_FromLong(0);
+	if (numerator == NULL) goto error;
+
+	long_methods = PyLong_Type.tp_as_number;
+
+	py_chunk = PyLong_FromLong(chunk_size);
+	if (py_chunk == NULL) goto error;
+
+	while (float_part != 0) {
+		/* invariant: abs(self) ==
+		   (numerator + float_part) * 2**exponent exactly */
+		long digit;
+		PyObject *py_digit;
+
+		PyFPE_START_PROTECT("as_integer_ratio", goto error);
+		/* Pull chunk_size bits out of float_part, into digits. */
+		float_part = ldexp(float_part, chunk_size);
+		digit = (long)float_part;
+		float_part -= digit;
+                /* 0 <= float_part < 1 */
+		exponent -= chunk_size;
+		PyFPE_END_PROTECT(float_part);
+
+		/* Shift digits into numerator. */
+		// numerator <<= chunk_size
+		INPLACE_UPDATE(numerator,
+			       long_methods->nb_lshift(numerator, py_chunk));
+		if (numerator == NULL) goto error;
+
+		// numerator |= digit
+		py_digit = PyLong_FromLong(digit);
+		if (py_digit == NULL) goto error;
+		INPLACE_UPDATE(numerator,
+			       long_methods->nb_or(numerator, py_digit));
+		Py_DECREF(py_digit);
+		if (numerator == NULL) goto error;
+	}
+
+	/* Add in the sign bit. */
+	if (is_negative) {
+		INPLACE_UPDATE(numerator,
+			       long_methods->nb_negative(numerator));
+		if (numerator == NULL) goto error;
+	}
+
+	/* now self = numerator * 2**exponent exactly; fold in 2**exponent */
+	denominator = PyLong_FromLong(1);
+	py_exponent = PyLong_FromLong(labs(exponent));
+	if (py_exponent == NULL) goto error;
+	INPLACE_UPDATE(py_exponent,
+		       long_methods->nb_lshift(denominator, py_exponent));
+	if (py_exponent == NULL) goto error;
+	if (exponent > 0) {
+		INPLACE_UPDATE(numerator,
+			       long_methods->nb_multiply(numerator,
+							 py_exponent));
+		if (numerator == NULL) goto error;
+	}
+	else {
+		Py_DECREF(denominator);
+		denominator = py_exponent;
+		py_exponent = NULL;
+	}
+
+	result_pair = PyTuple_Pack(2, numerator, denominator);
+
+#undef INPLACE_UPDATE
+error:
+	Py_XDECREF(py_exponent);
+	Py_XDECREF(py_chunk);
+	Py_XDECREF(denominator);
+	Py_XDECREF(numerator);
+	return result_pair;
+}
+
+PyDoc_STRVAR(float_as_integer_ratio_doc,
+"float.as_integer_ratio() -> (int, int)\n"
+"\n"
+"Returns a pair of integers, not necessarily in lowest terms, whose\n"
+"ratio is exactly equal to the original float. This method raises an\n"
+"OverflowError on infinities and a ValueError on nans. The resulting\n"
+"denominator will be positive.\n"
+"\n"
+">>> (10.0).as_integer_ratio()\n"
+"(167772160L, 16777216L)\n"
+">>> (0.0).as_integer_ratio()\n"
+"(0, 1)\n"
+">>> (-.25).as_integer_ratio()\n"
+"(-134217728L, 536870912L)");
+
 
 static PyObject *
 float_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds);
@@ -1281,6 +1438,8 @@
 	{"__round__",	(PyCFunction)float_round, METH_VARARGS,
          "Returns the Integral closest to x, rounding half toward even.\n"
          "When an argument is passed, works like built-in round(x, ndigits)."},
+	{"as_integer_ratio", (PyCFunction)float_as_integer_ratio, METH_NOARGS,
+	 float_as_integer_ratio_doc},
 	{"__getnewargs__",	(PyCFunction)float_getnewargs,	METH_NOARGS},
 	{"__getformat__",	(PyCFunction)float_getformat,	
 	 METH_O|METH_CLASS,		float_getformat_doc},