1 files changed, 1 insertions, 1 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 101ed73d3ef..4ea0e52efb7 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3009,7 +3009,7 @@ extern void syms_of_macros P_ ((void));
 /* defined in undo.c */
 extern Lisp_Object Qinhibit_read_only;
 EXFUN (Fundo_boundary, 0);
-extern Lisp_Object truncate_undo_list P_ ((Lisp_Object, int, int));
+extern Lisp_Object truncate_undo_list P_ ((Lisp_Object, int, int, int));
 extern void record_marker_adjustment P_ ((Lisp_Object, int));
 extern void record_insert P_ ((int, int));
 extern void record_delete P_ ((int, Lisp_Object));