diff -r 50164abbfc98 Objects/genobject.c
--- a/Objects/genobject.c	Mon Apr 08 20:59:11 2013 -0500
+++ b/Objects/genobject.c	Tue Apr 09 00:15:07 2013 -0400
@@ -173,17 +173,17 @@ gen_close_iter(PyObject *yf)
 }
 
 static PyObject *
 gen_yf(PyGenObject *gen)
 {
     PyObject *yf = NULL;
     PyFrameObject *f = gen->gi_frame;
 
-    if (f) {
+    if (f && f->f_stacktop) {
         PyObject *bytecode = f->f_code->co_code;
         unsigned char *code = (unsigned char *)PyBytes_AS_STRING(bytecode);
 
         if (code[f->f_lasti + 1] != YIELD_FROM)
             return NULL;
         yf = f->f_stacktop[-1];
         Py_INCREF(yf);
     }