Index: Python/pystate.c
===================================================================
--- Python/pystate.c	(revision 50704)
+++ Python/pystate.c	(working copy)
@@ -387,7 +387,54 @@
 	return tstate->next;
 }
 
+/* The implementation of sys._current_frames().  This is intended to be
+   called with the GIL held, as it will be when called via
+   sys._current_frames().  It's possible it would work fine even without
+   the GIL held, but haven't thought enough about that.
+*/
+PyObject *
+_PyThread_CurrentFrames(void)
+{
+	PyObject *result;
+	PyInterpreterState *i;
 
+	result = PyDict_New();
+	if (result == NULL)
+		return NULL;
+
+	/* for i in all interpreters:
+	 *     for t in all of i's thread states:
+	 *          if t's frame isn't NULL, map t's id to its frame
+	 * Because these lists can mutute even when the GIL is held, we
+	 * need to grab head_mutex for the duration.
+	 */
+	HEAD_LOCK();
+	for (i = interp_head; i != NULL; i = i->next) {
+		PyThreadState *t;
+		for (t = i->tstate_head; t != NULL; t = t->next) {
+			PyObject *id;
+			int stat;
+			struct _frame *frame = t->frame;
+			if (frame == NULL)
+				continue;
+			id = PyInt_FromLong(t->thread_id);
+			if (id == NULL)
+				goto Fail;
+			stat = PyDict_SetItem(result, id, (PyObject *)frame);
+			Py_DECREF(id);
+			if (stat < 0)
+				goto Fail;
+		}
+	}
+	HEAD_UNLOCK();
+	return result;
+
+ Fail:
+ 	HEAD_UNLOCK();
+ 	Py_DECREF(result);
+ 	return NULL;
+}
+
 /* Python "auto thread state" API. */
 #ifdef WITH_THREAD
 
@@ -550,54 +597,6 @@
 		PyEval_SaveThread();
 }
 
-/* The implementation of sys._current_frames().  This is intended to be
-   called with the GIL held, as it will be when called via
-   sys._current_frames().  It's possible it would work fine even without
-   the GIL held, but haven't thought enough about that.
-*/
-PyObject *
-_PyThread_CurrentFrames(void)
-{
-	PyObject *result;
-	PyInterpreterState *i;
-
-	result = PyDict_New();
-	if (result == NULL)
-		return NULL;
-
-	/* for i in all interpreters:
-	 *     for t in all of i's thread states:
-	 *          if t's frame isn't NULL, map t's id to its frame
-	 * Because these lists can mutute even when the GIL is held, we
-	 * need to grab head_mutex for the duration.
-	 */
-	HEAD_LOCK();
-	for (i = interp_head; i != NULL; i = i->next) {
-		PyThreadState *t;
-		for (t = i->tstate_head; t != NULL; t = t->next) {
-			PyObject *id;
-			int stat;
-			struct _frame *frame = t->frame;
-			if (frame == NULL)
-				continue;
-			id = PyInt_FromLong(t->thread_id);
-			if (id == NULL)
-				goto Fail;
-			stat = PyDict_SetItem(result, id, (PyObject *)frame);
-			Py_DECREF(id);
-			if (stat < 0)
-				goto Fail;
-		}
-	}
-	HEAD_UNLOCK();
-	return result;
-
- Fail:
- 	HEAD_UNLOCK();
- 	Py_DECREF(result);
- 	return NULL;
-}
-
 #ifdef __cplusplus
 }
 #endif
Index: Lib/test/test_sys.py
===================================================================
--- Lib/test/test_sys.py	(revision 50704)
+++ Lib/test/test_sys.py	(working copy)
@@ -239,9 +239,27 @@
 
     # sys._current_frames() is a CPython-only gimmick.
     def test_current_frames(self):
-        import threading, thread
+
+        try:
+            import threading, thread
+            have_threads = True
+        except ImportError:
+            # No threading support so sys._current_frames should
+            # return a dict with a single element, mapping the integer
+            # 0 to the main thread's frame.
+            have_threads = False
         import traceback
 
+        # test without using threads
+        if not have_threads:
+            current_frame = sys._current_frames()
+            self.assertEqual(len(current_frame), 1)
+            
+            f = sys._getframe()
+            self.assert_(f, current_frame[0])
+
+            return
+        
         # Spawn a thread that blocks at a known place.  Then the main
         # thread does sys._current_frames(), and verifies that the frames
         # returned make sense.