Index: Include/objimpl.h
===================================================================
--- Include/objimpl.h (revision 118072)
+++ Include/objimpl.h (working copy)
@@ -258,7 +258,7 @@
     double dummy;  /* force worst-case alignment */
 } PyGC_Head;

-extern PyGC_Head *_PyGC_generation0;
+PyAPI_DATA(PyGC_Head*) _PyGC_generation0;

 #define _Py_AS_GC(o) ((PyGC_Head *)(o)-1)