diff --git a/affinity/src/test/java/net/openhft/affinity/AffinityLockTest.java b/affinity/src/test/java/net/openhft/affinity/AffinityLockTest.java
index 939f58552..d0187b48a 100644
--- a/affinity/src/test/java/net/openhft/affinity/AffinityLockTest.java
+++ b/affinity/src/test/java/net/openhft/affinity/AffinityLockTest.java
@@ -324,6 +324,11 @@ public void testTooHighCpuId() {
         AffinityLock.acquireLock(123456);
     }
 
+    @Test(expected = IllegalArgumentException.class)
+    public void testNegativeCpuId() {
+        AffinityLock.acquireLock(-1);
+    }
+
     @Test(expected = IllegalArgumentException.class)
     public void testTooHighCpuId2() {
         AffinityLock.acquireLock(new int[]{123456});