diff --git a/lamport/clock_test.go b/lamport/clock_test.go
new file mode 100644
index 000000000..a30dec9bd
--- /dev/null
+++ b/lamport/clock_test.go
@@ -0,0 +1,22 @@
+// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
+// All rights reserved. Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package lamport
+
+import "testing"
+
+var inputs = []uint64{0, 42, 2, 3, 4, 8, 9, 33, 44, 112, 100}
+
+func TestClock(t *testing.T) {
+	c := Clock{}
+
+	var prev uint64
+	for _, input := range inputs {
+		cur := c.Tick(input)
+		if cur <= prev || cur <= input {
+			t.Error("Clock moving backwards")
+		}
+		prev = cur
+	}
+}