diff --git a/examples/util/clock.rs b/examples/util/clock.rs
new file mode 100644
index 0000000..8064950
--- /dev/null
+++ b/examples/util/clock.rs
@@ -0,0 +1,19 @@
+use smoltcp::time::{Duration, Instant};
+use core::cell::Cell;
+
+#[derive(Debug)]
+pub struct Clock(Cell<Instant>);
+
+impl Clock {
+    pub fn new() -> Clock {
+        Clock(Cell::new(Instant::from_millis(0)))
+    }
+
+    pub fn advance(&self, duration: Duration) {
+        self.0.set(self.0.get() + duration)
+    }
+
+    pub fn elapsed(&self) -> Instant {
+        self.0.get()
+    }
+}
\ No newline at end of file