diff --git a/Cargo.lock b/Cargo.lock
index 63d5d25..4aa76ba 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -167,6 +167,7 @@ version = "0.5.0"
 dependencies = [
  "anyhow",
  "image",
+ "libc",
  "log",
  "stderrlog",
  "structopt",
diff --git a/Cargo.toml b/Cargo.toml
index b01aa9b..cfd0fee 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,3 +15,4 @@ stderrlog = "0.5.1"
 xcb-util = { version = "0.3.0", features = ["image", "cursor"] }
 xcb = "0.9.0"
 structopt = "0.3.21"
+libc = "0.2.86"
diff --git a/src/singleton.rs b/src/singleton.rs
index 4729c6e..13ee12c 100644
--- a/src/singleton.rs
+++ b/src/singleton.rs
@@ -11,9 +11,8 @@ const PATHS: &[&str] = &["/var/run", "/tmp"];
 pub fn check_singleton() -> Result<Lockfile> {
     let (mut file, path) = get_lock_file()?;
 
-    let current_time = SystemTime::now().duration_since(UNIX_EPOCH)?.as_millis();
     let pid = process::id();
-    let contents = format!("{}:{}", current_time, pid).as_bytes().to_vec();
+    let contents = format!("{}", pid).as_bytes().to_vec();
     file.write_all(&contents)?;
 
     Ok(Lockfile(path))
@@ -40,15 +39,20 @@ fn get_lock_file() -> Result<(File, PathBuf)> {
             Ok(mut f) => {
                 let mut contents = String::new();
                 f.read_to_string(&mut contents)?;
+                let pid = contents.parse::<i32>()?;
 
-                let mut parts = contents.split(":");
-                let timestamp = parts.next().unwrap().parse::<u64>()?;
-                let pid = parts.next().unwrap();
-                let time = UNIX_EPOCH + Duration::from_millis(timestamp);
+                // let mut parts = contents.split(":");
+                // let timestamp = parts.next().unwrap().parse::<u64>()?;
+                // let pid = parts.next().unwrap();
+                // let time = UNIX_EPOCH + Duration::from_millis(timestamp);
 
-                // if it hasn't been 5 minutes since the last open, then bail
-                if SystemTime::now() - Duration::from_secs(60 * 5) < time {
-                    bail!("existing lockfile found for pid {} at time {:?}", pid, time);
+                // if the process that has the lockfile open is still running, bail
+                let status = unsafe {libc::kill(pid, 0)};
+
+                // 0 means the signal was successfully sent, which means it's still running
+                // if it's 0 then we bail
+                if status == 0 {
+                    bail!("existing lockfile for pid {}", pid);
                 }
             }
             // ignore errors