diff --git a/CHANGES.txt b/CHANGES.txt
index af5956fbb1a..21c07374889 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -381,6 +381,7 @@ Release 0.90.4 - Unreleased
                (Vandana Ayyalasomayajula via Ted Yu)
    HBASE-3984  CT.verifyRegionLocation isn't doing a very good check,
                can delay cluster recovery
+   HBASE-4045  [replication] NPE in ReplicationSource when ZK is gone
 
   IMPROVEMENT
    HBASE-3882  hbase-config.sh needs to be updated so it can auto-detects the
diff --git a/src/main/java/org/apache/hadoop/hbase/replication/ReplicationZookeeper.java b/src/main/java/org/apache/hadoop/hbase/replication/ReplicationZookeeper.java
index 4923bfbcf42..b6843b91269 100644
--- a/src/main/java/org/apache/hadoop/hbase/replication/ReplicationZookeeper.java
+++ b/src/main/java/org/apache/hadoop/hbase/replication/ReplicationZookeeper.java
@@ -219,16 +219,16 @@ public class ReplicationZookeeper {
   /**
    * Get the list of all the region servers from the specified peer
    * @param zkw zk connection to use
-   * @return list of region server addresses
+   * @return list of region server addresses or an empty list if the slave
+   * is unavailable
    */
   private List<ServerName> fetchSlavesAddresses(ZooKeeperWatcher zkw) {
-    List<ServerName> rss = null;
     try {
-      rss = listChildrenAndGetAsServerNames(zkw, zkw.rsZNode);
+      return listChildrenAndGetAsServerNames(zkw, zkw.rsZNode);
     } catch (KeeperException e) {
       LOG.warn("Cannot get peer's region server addresses", e);
+      return new ArrayList<ServerName>(0);
     }
-    return rss;
   }
 
   /**