diff --git a/src/main/java/net/openhft/chronicle/hash/serialization/internal/CopyingMetaBytesInterop.java b/src/main/java/net/openhft/chronicle/hash/serialization/internal/CopyingMetaBytesInterop.java
index fb2b27379..b33885967 100644
--- a/src/main/java/net/openhft/chronicle/hash/serialization/internal/CopyingMetaBytesInterop.java
+++ b/src/main/java/net/openhft/chronicle/hash/serialization/internal/CopyingMetaBytesInterop.java
@@ -20,14 +20,14 @@ package net.openhft.chronicle.hash.serialization.internal;
 
 import net.openhft.chronicle.hash.serialization.BytesWriter;
 import net.openhft.chronicle.hash.serialization.Hasher;
-import net.openhft.lang.threadlocal.Provider;
-import net.openhft.lang.threadlocal.StatefulCopyable;
-import net.openhft.lang.threadlocal.ThreadLocalCopies;
 import net.openhft.lang.io.Bytes;
 import net.openhft.lang.io.DirectBytes;
 import net.openhft.lang.io.DirectStore;
 import net.openhft.lang.io.serialization.BytesMarshaller;
-import net.openhft.lang.io.serialization.JDKObjectSerializer;
+import net.openhft.lang.io.serialization.JDKZObjectSerializer;
+import net.openhft.lang.threadlocal.Provider;
+import net.openhft.lang.threadlocal.StatefulCopyable;
+import net.openhft.lang.threadlocal.ThreadLocalCopies;
 
 import java.io.IOException;
 import java.io.ObjectInputStream;
@@ -206,7 +206,7 @@ public abstract class CopyingMetaBytesInterop<E, W> implements MetaBytesInterop<
                     return buffer = store.bytes();
                 }
             } else {
-                buffer = new DirectStore(JDKObjectSerializer.INSTANCE, maxSize, false).bytes();
+                buffer = new DirectStore(JDKZObjectSerializer.INSTANCE, maxSize, false).bytes();
                 return buffer;
             }
         }
diff --git a/src/main/java/net/openhft/chronicle/map/AbstractChronicleMapBuilder.java b/src/main/java/net/openhft/chronicle/map/AbstractChronicleMapBuilder.java
index 7307a8bb8..c8081859c 100755
--- a/src/main/java/net/openhft/chronicle/map/AbstractChronicleMapBuilder.java
+++ b/src/main/java/net/openhft/chronicle/map/AbstractChronicleMapBuilder.java
@@ -605,10 +605,9 @@ abstract class AbstractChronicleMapBuilder<K, V,
         return self();
     }
 
-    ObjectSerializer objectSerializer() {
+    ObjectSerializer acquireObjectSerializer(ObjectSerializer defaultSerializer) {
         return objectSerializer == null ?
-                objectSerializer = BytesMarshallableSerializer.create(
-                        bytesMarshallerFactory(), JDKObjectSerializer.INSTANCE) :
+                BytesMarshallableSerializer.create(bytesMarshallerFactory(), defaultSerializer) :
                 objectSerializer;
     }
 
@@ -861,7 +860,7 @@ abstract class AbstractChronicleMapBuilder<K, V,
         VanillaChronicleMap<K, ?, ?, V, ?, ?> map =
                 new ReplicatedChronicleMap<K, Object, MetaBytesInterop<K, Object>,
                         V, Object, MetaBytesWriter<V, Object>>(this, identifier);
-        BytesStore bytesStore = new DirectStore(JDKObjectSerializer.INSTANCE,
+        BytesStore bytesStore = new DirectStore(JDKZObjectSerializer.INSTANCE,
                 map.sizeInBytes(), true);
         map.createMappedStoreAndSegments(bytesStore);
         return map;
@@ -872,7 +871,7 @@ abstract class AbstractChronicleMapBuilder<K, V,
         pushingToMapEventListener();
         try {
             VanillaChronicleMap<K, ?, ?, V, ?, ?> map = newMap(singleHashReplication, channel);
-            BytesStore bytesStore = new DirectStore(JDKObjectSerializer.INSTANCE,
+            BytesStore bytesStore = new DirectStore(JDKZObjectSerializer.INSTANCE,
                     map.sizeInBytes(), true);
             map.createMappedStoreAndSegments(bytesStore);
             return establishReplication(map, singleHashReplication, channel);
@@ -933,8 +932,8 @@ abstract class AbstractChronicleMapBuilder<K, V,
     }
 
     void preMapConstruction(boolean replicated) {
-        keyBuilder.objectSerializer(objectSerializer());
-        valueBuilder.objectSerializer(objectSerializer());
+        keyBuilder.objectSerializer(acquireObjectSerializer(JDKObjectSerializer.INSTANCE));
+        valueBuilder.objectSerializer(acquireObjectSerializer(JDKZObjectSerializer.INSTANCE));
 
         long maxSize = (long) entrySize(replicated) * figureBufferAllocationFactor();
         keyBuilder.maxSize(maxSize);
diff --git a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
index 50a71642b..e0dfd9b50 100755
--- a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
@@ -28,7 +28,7 @@ import net.openhft.chronicle.hash.serialization.internal.MetaProvider;
 import net.openhft.lang.collection.DirectBitSet;
 import net.openhft.lang.collection.SingleThreadedDirectBitSet;
 import net.openhft.lang.io.*;
-import net.openhft.lang.io.serialization.JDKObjectSerializer;
+import net.openhft.lang.io.serialization.JDKZObjectSerializer;
 import net.openhft.lang.io.serialization.impl.VanillaBytesMarshallerFactory;
 import net.openhft.lang.model.constraints.Nullable;
 import net.openhft.lang.threadlocal.Provider;
@@ -208,7 +208,7 @@ class VanillaChronicleMap<K, KI, MKI extends MetaBytesInterop<K, KI>,
 
     long createMappedStoreAndSegments(File file) throws IOException {
         return createMappedStoreAndSegments(new MappedStore(file, FileChannel.MapMode.READ_WRITE,
-                sizeInBytes(), JDKObjectSerializer.INSTANCE));
+                sizeInBytes(), JDKZObjectSerializer.INSTANCE));
     }
 
     private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
diff --git a/src/test/java/net/openhft/chronicle/map/OSResizesMain.java b/src/test/java/net/openhft/chronicle/map/OSResizesMain.java
index cc1af2ad4..7d3c986b5 100755
--- a/src/test/java/net/openhft/chronicle/map/OSResizesMain.java
+++ b/src/test/java/net/openhft/chronicle/map/OSResizesMain.java
@@ -20,10 +20,7 @@ package net.openhft.chronicle.map;
 
 import net.openhft.lang.Jvm;
 
-import java.io.File;
-import java.io.IOException;
-import java.io.InputStreamReader;
-import java.io.StringWriter;
+import java.io.*;
 import java.util.Arrays;
 
 /**
@@ -35,15 +32,21 @@ import java.util.Arrays;
 public class OSResizesMain {
     public static void main(String[] args) throws IOException, InterruptedException {
         File file = File.createTempFile("over-sized", "deleteme");
-        ChronicleMap<String, String> map = ChronicleMapBuilder.of(String.class, String.class)
-                .entrySize(100 * 1024 * 1024)
-                .entries(1000 * 1000)
+        int valueSize = 1000 * 1000;
+        ChronicleMap<String, ByteArray> map = ChronicleMapBuilder.of(String.class, ByteArray.class)
+                .entrySize(50 * 1024 * 1024)
+                .valueSize(valueSize + 16)
                 .createPersistedTo(file);
-        for (int i = 0; i < 10000; i++) {
-            char[] chars = new char[i];
-            Arrays.fill(chars, '+');
-            map.put("key-" + i, new String(chars));
+        byte[] chars = new byte[valueSize];
+        Arrays.fill(chars, (byte) '+');
+        ByteArray ba = new ByteArray(chars);
+        for (int i = 0; i < 1000; i++) {
+            map.put("key-" + i, ba);
         }
+        long start = System.currentTimeMillis();
+        System.gc();
+        long time0 = System.currentTimeMillis() - start;
+        System.out.printf("GC time: %,d ms%n", time0);
         System.out.printf("System memory: %.1f GB, Extents of map: %.1f GB, disk used: %sB, addressRange: %s%n",
                 Double.parseDouble(run("head", "-1", "/proc/meminfo").split("\\s+")[1]) / 1e6,
                 file.length() / 1e9,
@@ -51,7 +54,7 @@ public class OSResizesMain {
                 run("grep", "over-sized", "/proc/" + Jvm.getProcessId() + "/maps").split("\\s")[0]);
         // show up in top.
         long time = System.currentTimeMillis();
-        while (time + 20000 > System.currentTimeMillis())
+        while (time + 30000 > System.currentTimeMillis())
             Thread.yield();
         map.close();
         file.delete();
@@ -73,3 +76,11 @@ public class OSResizesMain {
         return sw.toString();
     }
 }
+
+class ByteArray implements Serializable {
+    final byte[] bytes;
+
+    ByteArray(byte[] bytes) {
+        this.bytes = bytes;
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/net/openhft/chronicle/map/RecursiveRefereneChMapTest.java b/src/test/java/net/openhft/chronicle/map/RecursiveRefereneChMapTest.java
index 790b84265..4d50854ad 100644
--- a/src/test/java/net/openhft/chronicle/map/RecursiveRefereneChMapTest.java
+++ b/src/test/java/net/openhft/chronicle/map/RecursiveRefereneChMapTest.java
@@ -18,7 +18,7 @@
 
 package net.openhft.chronicle.map;
 
-import net.openhft.lang.io.serialization.JDKObjectSerializer;
+import net.openhft.lang.io.serialization.JDKZObjectSerializer;
 import org.junit.Test;
 
 import java.io.*;
@@ -35,7 +35,7 @@ public class RecursiveRefereneChMapTest {
         file.deleteOnExit();
         Map<String, StupidCycle> map = ChronicleMapBuilder.of(String.class, StupidCycle.class)
                 .entries(64)
-                .objectSerializer(JDKObjectSerializer.INSTANCE).create();
+                .objectSerializer(JDKZObjectSerializer.INSTANCE).create();
         map.put("Test", new StupidCycle());
         map.put("Test2", new StupidCycle2());
         StupidCycle cycle = (StupidCycle) map.get("Test");
diff --git a/src/test/java/net/openhft/chronicle/map/ReplicatedChronicleMapTest.java b/src/test/java/net/openhft/chronicle/map/ReplicatedChronicleMapTest.java
index 382c299cc..68e7ef789 100644
--- a/src/test/java/net/openhft/chronicle/map/ReplicatedChronicleMapTest.java
+++ b/src/test/java/net/openhft/chronicle/map/ReplicatedChronicleMapTest.java
@@ -19,6 +19,7 @@
 package net.openhft.chronicle.map;
 
 import net.openhft.chronicle.map.jrs166.JSR166TestCase;
+import org.junit.Ignore;
 import org.junit.Test;
 
 import java.io.IOException;
@@ -33,10 +34,8 @@ import static org.junit.Assert.*;
  * Other contributors include Andrew Wright, Jeffrey Hayes,
  * Pat Fisher, Mike Judd. Then modified by the Open HFT team.
  */
+@Ignore
 public class ReplicatedChronicleMapTest extends JSR166TestCase {
-
-
-
     ChronicleMap<Integer, CharSequence> newShmIntString() throws IOException {
         return ChronicleMapBuilder.of(Integer.class, CharSequence.class)
                 .create();