diff --git a/src/proto/undo.pro b/src/proto/undo.pro
index baa98c4..daac377 100644
--- a/src/proto/undo.pro
+++ b/src/proto/undo.pro
@@ -24,4 +24,5 @@
 void u_blockfree __ARGS((buf_T *buf));
 int bufIsChanged __ARGS((buf_T *buf));
 int curbufIsChanged __ARGS((void));
+void u_eval_tree __ARGS((u_header_T *first_uhp, list_T *list));
 /* vim: set ft=c : */