diff --git a/src/proto/os_mac_conv.pro b/src/proto/os_mac_conv.pro
index 1ab9d28..7aa3d9f 100644
--- a/src/proto/os_mac_conv.pro
+++ b/src/proto/os_mac_conv.pro
@@ -1,10 +1,11 @@
-extern char_u *mac_string_convert __ARGS((char_u *ptr, int len, int *lenp, int fail_on_error, int from, int to, int *unconvlenp));
-extern int macroman2enc __ARGS((char_u *ptr, long *sizep, long real_size));
-extern int enc2macroman __ARGS((char_u *from, size_t fromlen, char_u *to, int *tolenp, int maxtolen, char_u *rest, int *restlenp));
-
-extern void	    mac_conv_init __ARGS((void));
-extern void	    mac_conv_cleanup __ARGS((void));
-extern char_u	    *mac_utf16_to_enc __ARGS((UniChar *from, size_t fromLen, size_t *actualLen));
-extern UniChar	    *mac_enc_to_utf16 __ARGS((char_u *from, size_t fromLen, size_t *actualLen));
-extern CFStringRef  mac_enc_to_cfstring __ARGS((char_u *from, size_t fromLen));
-extern char_u	    *mac_precompose_path __ARGS((char_u *decompPath, size_t decompLen, size_t *precompLen));
+/* os_mac_conv.c */
+char_u *mac_string_convert __ARGS((char_u *ptr, int len, int *lenp, int fail_on_error, int from_enc, int to_enc, int *unconvlenp));
+int macroman2enc __ARGS((char_u *ptr, long *sizep, long real_size));
+int enc2macroman __ARGS((char_u *from, size_t fromlen, char_u *to, int *tolenp, int maxtolen, char_u *rest, int *restlenp));
+void mac_conv_init __ARGS((void));
+void mac_conv_cleanup __ARGS((void));
+char_u *mac_utf16_to_enc __ARGS((UniChar *from, size_t fromLen, size_t *actualLen));
+UniChar *mac_enc_to_utf16 __ARGS((char_u *from, size_t fromLen, size_t *actualLen));
+CFStringRef mac_enc_to_cfstring __ARGS((char_u *from, size_t fromLen));
+char_u *mac_precompose_path __ARGS((char_u *decompPath, size_t decompLen, size_t *precompLen));
+/* vim: set ft=c : */