diff --git a/src/main/java/net/schmizz/concurrent/Promise.java b/src/main/java/net/schmizz/concurrent/Promise.java
index 06b4a835..5b8372ca 100644
--- a/src/main/java/net/schmizz/concurrent/Promise.java
+++ b/src/main/java/net/schmizz/concurrent/Promise.java
@@ -136,7 +136,7 @@ public V retrieve(long timeout, TimeUnit unit)
             throws T {
         final V value = tryRetrieve(timeout, unit);
         if (value == null)
-            throw chainer.chain(new TimeoutException("Timeout expired"));
+            throw chainer.chain(new TimeoutException("Timeout expired: " + timeout + " " + unit));
         else
             return value;
     }