-extern void evaporate_overlays (EMACS_INT);
-extern int overlays_at (EMACS_INT pos, int extend, Lisp_Object **vec_ptr,
- int *len_ptr, EMACS_INT *next_ptr,
- EMACS_INT *prev_ptr, int change_req);
-extern int sort_overlays (Lisp_Object *, int, struct window *);
-extern void recenter_overlay_lists (struct buffer *, EMACS_INT);
-extern EMACS_INT overlay_strings (EMACS_INT, struct window *, unsigned char **);
+extern void evaporate_overlays (ptrdiff_t);
+extern ptrdiff_t overlays_at (EMACS_INT pos, int extend, Lisp_Object **vec_ptr,
+ ptrdiff_t *len_ptr, ptrdiff_t *next_ptr,
+ ptrdiff_t *prev_ptr, int change_req);
+extern ptrdiff_t sort_overlays (Lisp_Object *, ptrdiff_t, struct window *);
+extern void recenter_overlay_lists (struct buffer *, ptrdiff_t);
+extern ptrdiff_t overlay_strings (ptrdiff_t, struct window *, unsigned char **);