diff --git a/src/proto/ex_docmd.pro b/src/proto/ex_docmd.pro
index e267acf..8b0bd7c 100644
--- a/src/proto/ex_docmd.pro
+++ b/src/proto/ex_docmd.pro
@@ -52,4 +52,5 @@
 int put_eol __ARGS((FILE *fd));
 int put_line __ARGS((FILE *fd, char *s));
 void dialog_msg __ARGS((char_u *buff, char *format, char_u *fname));
+char_u *get_behave_arg __ARGS((expand_T *xp, int idx));
 /* vim: set ft=c : */