diff --git a/src/proto/winclip.pro b/src/proto/winclip.pro
index 996847e..5eee35d 100644
--- a/src/proto/winclip.pro
+++ b/src/proto/winclip.pro
@@ -11,4 +11,5 @@
 short_u *enc_to_utf16 __ARGS((char_u *str, int *lenp));
 char_u *utf16_to_enc __ARGS((short_u *str, int *lenp));
 void acp_to_enc __ARGS((char_u *str, int str_size, char_u **out, int *outlen));
+void enc_to_acp __ARGS((char_u *str, int str_size, char_u **out, int *outlen));
 /* vim: set ft=c : */