diff --git a/src/proto/map.pro b/src/proto/map.pro
index 3592623..42ebd4b 100644
--- a/src/proto/map.pro
+++ b/src/proto/map.pro
@@ -10,7 +10,7 @@
 char_u *set_context_in_map_cmd(expand_T *xp, char_u *cmd, char_u *arg, int forceit, int isabbrev, int isunmap, cmdidx_T cmdidx);
 int ExpandMappings(regmatch_T *regmatch, int *num_file, char_u ***file);
 int check_abbr(int c, char_u *ptr, int col, int mincol);
-char_u *eval_map_expr(char_u *str, int c);
+char_u *eval_map_expr(mapblock_T *mp, int c);
 char_u *vim_strsave_escape_csi(char_u *p);
 void vim_unescape_csi(char_u *p);
 int makemap(FILE *fd, buf_T *buf);