diff --git a/CHANGES.txt b/CHANGES.txt
index cec907be6fd..b2076eaf360 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -396,6 +396,7 @@ Release 0.21.0 - Unreleased
    HBASE-2725  Shutdown hook management is gone in trunk; restore
    HBASE-2740  NPE in ReadWriteConsistencyControl
    HBASE-2752  Don't retry forever when waiting on too many store files
+   HBASE-2737  CME in ZKW introduced in HBASE-2694 (Karthik Ranganathan via JD)
 
   IMPROVEMENTS
    HBASE-1760  Cleanup TODOs in HTable
diff --git a/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWrapper.java b/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWrapper.java
index 9f346026569..b26c071839e 100644
--- a/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWrapper.java
+++ b/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWrapper.java
@@ -219,11 +219,11 @@ public class ZooKeeperWrapper implements Watcher {
     }    
   }
 
-  public void registerListener(Watcher watcher) {
+  public synchronized void registerListener(Watcher watcher) {
     listeners.add(watcher);
   }
 
-  public void unregisterListener(Watcher watcher) {
+  public synchronized void unregisterListener(Watcher watcher) {
     listeners.remove(watcher);
   }