diff --git a/src/proto/os_unix.pro b/src/proto/os_unix.pro
index cfdf0ed..46230dc 100644
--- a/src/proto/os_unix.pro
+++ b/src/proto/os_unix.pro
@@ -57,6 +57,7 @@
 void mch_set_shellsize(void);
 void mch_new_shellsize(void);
 int mch_parse_cmd(char_u *cmd, int use_shcf, char ***argv, int *argc);
+void may_send_sigint(int c, pid_t pid, pid_t wpid);
 int mch_call_shell(char_u *cmd, int options);
 void mch_job_start(char **argv, job_T *job, jobopt_T *options);
 char *mch_job_status(job_T *job);