diff --git a/src/main/java/rx/subscriptions/CompositeSubscription.java b/src/main/java/rx/subscriptions/CompositeSubscription.java
index fea7b70910..777b18f04d 100644
--- a/src/main/java/rx/subscriptions/CompositeSubscription.java
+++ b/src/main/java/rx/subscriptions/CompositeSubscription.java
@@ -1,12 +1,12 @@
 /**
  * Copyright 2014 Netflix, Inc.
- * 
+ *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  * http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -55,6 +55,9 @@ public synchronized boolean isUnsubscribed() {
      *          the {@link Subscription} to add
      */
     public void add(final Subscription s) {
+        if (s.isUnsubscribed()) {
+            return;
+        }
         Subscription unsubscribe = null;
         synchronized (this) {
             if (unsubscribed) {
diff --git a/src/test/java/rx/subscriptions/CompositeSubscriptionTest.java b/src/test/java/rx/subscriptions/CompositeSubscriptionTest.java
index 4cff2a3e6a..18ac45f198 100644
--- a/src/test/java/rx/subscriptions/CompositeSubscriptionTest.java
+++ b/src/test/java/rx/subscriptions/CompositeSubscriptionTest.java
@@ -337,4 +337,11 @@ public void testTryRemoveIfNotIn() {
         
         csub.remove(csub1); // try removing agian
     }
+
+    @Test(expected = NullPointerException.class)
+    public void testAddingNullSubscriptionIllegal() {
+        CompositeSubscription csub = new CompositeSubscription();
+        csub.add(null);
+    }
+
 }