diff --git a/activemq-core/src/main/java/org/apache/activemq/openwire/OpenWireFormat.java b/activemq-core/src/main/java/org/apache/activemq/openwire/OpenWireFormat.java
index b27dac55de..4366668613 100755
--- a/activemq-core/src/main/java/org/apache/activemq/openwire/OpenWireFormat.java
+++ b/activemq-core/src/main/java/org/apache/activemq/openwire/OpenWireFormat.java
@@ -57,8 +57,8 @@ final public class OpenWireFormat implements WireFormat {
     private short nextMarshallCacheIndex=0;    
     private short nextMarshallCacheEvictionIndex=0;    
     private HashMap marshallCacheMap = new HashMap();
-    private DataStructure marshallCache[];
-    private DataStructure unmarshallCache[];
+    private DataStructure marshallCache[] = new DataStructure[MARSHAL_CACHE_SIZE];
+    private DataStructure unmarshallCache[] = new DataStructure[MARSHAL_CACHE_SIZE];
     
 	private WireFormatInfo preferedWireFormatInfo;