diff --git a/tokio/src/net/unix/ucred.rs b/tokio/src/net/unix/ucred.rs
index 466aedc21fe..b6ced17b559 100644
--- a/tokio/src/net/unix/ucred.rs
+++ b/tokio/src/net/unix/ucred.rs
@@ -1,8 +1,10 @@
-use libc::{gid_t, uid_t};
+use libc::{pid_t, gid_t, uid_t};
 
 /// Credentials of a process
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
 pub struct UCred {
+    /// PID (process ID) of the process
+    pub pid: Option<pid_t>, // TODO: how to get it under macos?
     /// UID (user ID) of the process
     pub uid: uid_t,
     /// GID (group ID) of the process
@@ -63,6 +65,7 @@ pub(crate) mod impl_linux {
             );
             if ret == 0 && ucred_size as usize == mem::size_of::<ucred>() {
                 Ok(super::UCred {
+                    pid: Some(ucred.pid),
                     uid: ucred.uid,
                     gid: ucred.gid,
                 })
@@ -100,6 +103,7 @@ pub(crate) mod impl_macos {
 
             if ret == 0 {
                 Ok(super::UCred {
+                    pid: None,
                     uid: uid.assume_init(),
                     gid: gid.assume_init(),
                 })
@@ -142,7 +146,7 @@ pub(crate) mod impl_solaris {
 
                 ucred_free(cred);
 
-                Ok(super::UCred { uid, gid })
+                Ok(super::UCred { pid: None, uid, gid })
             } else {
                 Err(io::Error::last_os_error())
             }