diff --git a/Include/tupleobject.h b/Include/tupleobject.h
index b5f2230..8fe28a2 100644
--- a/Include/tupleobject.h
+++ b/Include/tupleobject.h
@@ -58,6 +58,7 @@
 extern object *gettupleitem PROTO((object *, int));
 extern int settupleitem PROTO((object *, int, object *));
 extern object *gettupleslice PROTO((object *, int, int));
+extern int resizetuple PROTO((object **, int));
 
 /* Macro, trading safety for speed */
 #define GETTUPLEITEM(op, i) ((op)->ob_item[i])