diff --git a/src/proto/highlight.pro b/src/proto/highlight.pro
index 33f90c6..5318258 100644
--- a/src/proto/highlight.pro
+++ b/src/proto/highlight.pro
@@ -43,6 +43,7 @@
 void set_context_in_highlight_cmd(expand_T *xp, char_u *arg);
 char_u *get_highlight_name(expand_T *xp, int idx);
 char_u *get_highlight_name_ext(expand_T *xp, int idx, int skip_cleared);
+int expand_highlight_group( char_u *pat, expand_T *xp, regmatch_T *rmp, char_u ***matches, int *numMatches);
 void free_highlight_fonts(void);
 void f_hlget(typval_T *argvars, typval_T *rettv);
 void f_hlset(typval_T *argvars, typval_T *rettv);