diff --git a/pidof.1 b/pidof.1
index 1368704c..8ef4abfb 100644
--- a/pidof.1
+++ b/pidof.1
@@ -15,7 +15,7 @@
 .\" along with this program; if not, write to the Free Software
 .\" Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 .\"
-.TH PIDOF 1 "2018-03-03" "" "User Commands"
+.TH PIDOF 1 "2019-09-21" "" "User Commands"
 .SH NAME
 pidof -- find the process ID of a running program.
 .SH SYNOPSIS
@@ -52,6 +52,8 @@ program, in other words the calling shell or shell script.
 .IP "-S \fIseparator\fP"
 Use \fIseparator\fP as a separator put between pids. Used only when
 more than one pids are printed for the program.
+The \fI\-d\fR option is an alias for this option for sysvinit pidof
+compatibility.
 .SH "EXIT STATUS"
 .TP
 .B 0
diff --git a/pidof.c b/pidof.c
index f329d97d..b0d08cc4 100644
--- a/pidof.c
+++ b/pidof.c
@@ -289,13 +289,13 @@ int main (int argc, char **argv)
 	int first_pid = 1;
 
 	const char *separator = " ";
-	const char *opts = "scnxmo:S:?Vh";
+	const char *opts = "scdnxmo:S:?Vh";
 
 	static const struct option longopts[] = {
 		{"check-root", no_argument, NULL, 'c'},
 		{"single-shot", no_argument, NULL, 's'},
 		{"omit-pid", required_argument, NULL, 'o'},
-		{"separator", required_argument, NULL, 's'},
+		{"separator", required_argument, NULL, 'S'},
 		{"help", no_argument, NULL, 'h'},
 		{"version", no_argument, NULL, 'V'},
 		{NULL, 0, NULL, 0}
@@ -328,6 +328,7 @@ int main (int argc, char **argv)
 				pidof_root = pid_link(getpid(), "root");
 			}
 			break;
+		case 'd': /* sysv pidof uses this for S */
 		case 'S':
 			separator = optarg;
 			break;