diff -r d00a1c46fff7 Objects/longobject.c
--- a/Objects/longobject.c	Thu Feb 04 14:08:23 2016 -0500
+++ b/Objects/longobject.c	Thu Feb 04 20:52:15 2016 -0500
@@ -2765,6 +2765,10 @@
         PyErr_BadInternalCall();
         return -1.0;
     }
+    if (PyLong_CheckExact(v) && Py_ABS(Py_SIZE(v)) <= 1) {
+        /* fast path; single digit will always fit decimal */
+        return (double)MEDIUM_VALUE((PyLongObject *)v);
+    }
     if (!PyLong_Check(v)) {
         PyErr_SetString(PyExc_TypeError, "an integer is required");
         return -1.0;