diff --git a/src/os_unix.c b/src/os_unix.c
index 6f36553..6b26b06 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -5390,6 +5390,10 @@
     return NULL;
 }
 
+/*
+ * Send a (deadly) signal to "job".
+ * Return FAIL if "how" is not a valid name.
+ */
     int
 mch_stop_job(job_T *job, char_u *how)
 {