diff --git a/src/proto/os_unix.pro b/src/proto/os_unix.pro
index 86e12a0..14cde4a 100644
--- a/src/proto/os_unix.pro
+++ b/src/proto/os_unix.pro
@@ -59,6 +59,7 @@
 int mch_report_winsize(int fd, int rows, int cols);
 void mch_set_shellsize(void);
 void mch_new_shellsize(void);
+int unix_build_argv(char_u *cmd, char ***argvp, char_u **sh_tofree, char_u **shcf_tofree);
 int mch_call_shell(char_u *cmd, int options);
 void mch_job_start(char **argv, job_T *job, jobopt_T *options, int is_terminal);
 char *mch_job_status(job_T *job);