diff --git a/hystrix-core/src/main/java/com/netflix/hystrix/strategy/concurrency/HystrixConcurrencyStrategy.java b/hystrix-core/src/main/java/com/netflix/hystrix/strategy/concurrency/HystrixConcurrencyStrategy.java
index 406d5f1a0..e4e6039ac 100644
--- a/hystrix-core/src/main/java/com/netflix/hystrix/strategy/concurrency/HystrixConcurrencyStrategy.java
+++ b/hystrix-core/src/main/java/com/netflix/hystrix/strategy/concurrency/HystrixConcurrencyStrategy.java
@@ -36,6 +36,10 @@
  * For example, every {@link Callable} executed by {@link HystrixCommand} will call {@link #wrapCallable(Callable)} to give a chance for custom implementations to decorate the {@link Callable} with
  * additional behavior.
  * <p>
+ * When you implement a concrete {@link HystrixConcurrencyStrategy}, you should make the strategy idempotent w.r.t ThreadLocals.
+ * Since the usage of threads by Hystrix is internal, Hystrix does not attempt to apply the strategy in an idempotent way.
+ * Instead, you should write your strategy to work idempotently.  See https://github.com/Netflix/Hystrix/issues/351 for a more detailed discussion.
+ * <p>
  * See {@link HystrixPlugins} or the Hystrix GitHub Wiki for information on configuring plugins: <a
  * href="https://github.com/Netflix/Hystrix/wiki/Plugins">https://github.com/Netflix/Hystrix/wiki/Plugins</a>.
  */