diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index 4640e35b70..b9c9e2e3ef 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -214,6 +214,8 @@ Release 2.1.1-beta - UNRELEASED
     YARN-540. Race condition causing RM to potentially relaunch already
     unregistered AMs on RM restart (Jian He via bikas)
 
+    YARN-1184. ClassCastException during preemption enforcement. (cdouglas)
+
 Release 2.1.0-beta - 2013-08-22
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/LeafQueue.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/LeafQueue.java
index 8624ec0e87..a05b6d3bb0 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/LeafQueue.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/LeafQueue.java
@@ -1609,9 +1609,12 @@ public void recoverContainer(Resource clusterResource,
 
   }
 
-  // need to access the list of apps from the preemption monitor
+  /**
+   * Obtain (read-only) collection of active applications.
+   */
   public Set<FiCaSchedulerApp> getApplications() {
-    return Collections.unmodifiableSet(activeApplications);
+    // need to access the list of apps from the preemption monitor
+    return activeApplications;
   }
 
   // return a single Resource capturing the overal amount of pending resources