diff --git a/src/proto/charset.pro b/src/proto/charset.pro
index c915c58..a747319 100644
--- a/src/proto/charset.pro
+++ b/src/proto/charset.pro
@@ -20,6 +20,7 @@
 int linetabsize_col(int startcol, char_u *s);
 int win_linetabsize(win_T *wp, linenr_T lnum, char_u *line, colnr_T len);
 int linetabsize(win_T *wp, linenr_T lnum);
+int linetabsize_no_outer(win_T *wp, linenr_T lnum);
 void win_linetabsize_cts(chartabsize_T *cts, colnr_T len);
 int vim_isIDc(int c);
 int vim_isNormalIDc(int c);