diff --git a/src/proto/diff.pro b/src/proto/diff.pro
index 2ab6c54..b18c59b 100644
--- a/src/proto/diff.pro
+++ b/src/proto/diff.pro
@@ -27,4 +27,6 @@
 int diff_move_to(int dir, long count);
 linenr_T diff_get_corresponding_line(buf_T *buf1, linenr_T lnum1);
 linenr_T diff_lnum_win(linenr_T lnum, win_T *wp);
+void f_diff_filler(typval_T *argvars, typval_T *rettv);
+void f_diff_hlID(typval_T *argvars, typval_T *rettv);
 /* vim: set ft=c : */