diff --git a/src/uu/pidof/src/pidof.rs b/src/uu/pidof/src/pidof.rs
index e0dbb12..dd71936 100644
--- a/src/uu/pidof/src/pidof.rs
+++ b/src/uu/pidof/src/pidof.rs
@@ -137,6 +137,7 @@ pub fn uu_app() -> Command {
             Arg::new("o")
                 .short('o')
                 .help("Omit results with a given PID")
+                .value_delimiter(',')
                 .action(ArgAction::Append)
                 .value_parser(clap::value_parser!(usize))
                 .value_name("omitpid"),
diff --git a/tests/by-util/test_pidof.rs b/tests/by-util/test_pidof.rs
index 4c15eb9..c06c4bc 100644
--- a/tests/by-util/test_pidof.rs
+++ b/tests/by-util/test_pidof.rs
@@ -33,3 +33,9 @@ fn test_no_program() {
 fn test_no_pid_found() {
     new_ucmd!().arg("NO_THIS_PROGRAM").fails().code_is(1);
 }
+
+#[test]
+#[cfg(target_os = "linux")]
+fn test_quiet() {
+    new_ucmd!().arg("kthreadd").arg("-q").succeeds().no_output();
+}