diff --git a/kernel/src/syscall/timerfd_settime.rs b/kernel/src/syscall/timerfd_settime.rs
index f67540ec2..8cf94a852 100644
--- a/kernel/src/syscall/timerfd_settime.rs
+++ b/kernel/src/syscall/timerfd_settime.rs
@@ -6,7 +6,12 @@ use super::SyscallReturn;
 use crate::{
     fs::file_table::FileDesc,
     prelude::*,
-    time::{itimerspec_t, timer::Timeout, timerfd::TimerfdFile, timespec_t, TIMER_ABSTIME},
+    time::{
+        itimerspec_t,
+        timer::Timeout,
+        timerfd::{TFDSetTimeFlags, TimerfdFile},
+        timespec_t,
+    },
 };
 
 pub fn sys_timerfd_settime(
@@ -16,6 +21,8 @@ pub fn sys_timerfd_settime(
     old_itimerspec_addr: Vaddr,
     ctx: &Context,
 ) -> Result<SyscallReturn> {
+    let flags = TFDSetTimeFlags::from_bits(flags as u32)
+        .ok_or_else(|| Error::with_message(Errno::EINVAL, "invalid flags for timerfd_settime"))?;
     let file_table = ctx.thread_local.borrow_file_table();
     let file_table_locked = file_table.unwrap().read();
     let timerfd_file = file_table_locked.get_file(fd as _)?;
@@ -45,16 +52,15 @@ pub fn sys_timerfd_settime(
     // when the timer is rearmed.
     timerfd_file.clear_ticks();
 
-    const TFD_TIMER_CANCEL_ON_SET: i32 = 2;
     if expire_time != Duration::ZERO {
-        let timeout = if flags == 0 {
-            Timeout::After(expire_time)
-        } else if flags == TIMER_ABSTIME {
-            Timeout::When(expire_time)
-        } else if flags == TFD_TIMER_CANCEL_ON_SET {
+        if flags.contains(TFDSetTimeFlags::TFD_TIMER_CANCEL_ON_SET) {
             unimplemented!()
+        }
+
+        let timeout = if flags.contains(TFDSetTimeFlags::TFD_TIMER_ABSTIME) {
+            Timeout::When(expire_time)
         } else {
-            unreachable!()
+            Timeout::After(expire_time)
         };
         timer.set_timeout(timeout);
     }
diff --git a/kernel/src/time/timerfd.rs b/kernel/src/time/timerfd.rs
index 996ff63e9..fcf6bc87c 100644
--- a/kernel/src/time/timerfd.rs
+++ b/kernel/src/time/timerfd.rs
@@ -27,13 +27,21 @@ pub struct TimerfdFile {
 }
 
 bitflags! {
-    /// The flags useds for timerfd-related operations.
+    /// The flags used for timerfd-related operations.
     pub struct TFDFlags: u32 {
         const TFD_CLOEXEC = CreationFlags::O_CLOEXEC.bits();
         const TFD_NONBLOCK = StatusFlags::O_NONBLOCK.bits();
     }
 }
 
+bitflags! {
+    /// The flags used for timerfd settime operations.
+    pub struct TFDSetTimeFlags: u32 {
+        const TFD_TIMER_ABSTIME = 0x1;
+        const TFD_TIMER_CANCEL_ON_SET = 0x2;
+    }
+}
+
 impl TimerfdFile {
     /// Creates a new `TimerfdFile` instance.
     pub fn new(clockid: clockid_t, flags: TFDFlags, ctx: &Context) -> Result<Self> {