diff --git a/src/main/java/net/openhft/chronicle/map/AbstractChronicleMapBuilder.java b/src/main/java/net/openhft/chronicle/map/AbstractChronicleMapBuilder.java
index 4000c60e4..c8081859c 100755
--- a/src/main/java/net/openhft/chronicle/map/AbstractChronicleMapBuilder.java
+++ b/src/main/java/net/openhft/chronicle/map/AbstractChronicleMapBuilder.java
@@ -607,8 +607,7 @@ abstract class AbstractChronicleMapBuilder<K, V,
 
     ObjectSerializer acquireObjectSerializer(ObjectSerializer defaultSerializer) {
         return objectSerializer == null ?
-                objectSerializer = BytesMarshallableSerializer.create(
-                        bytesMarshallerFactory(), defaultSerializer) :
+                BytesMarshallableSerializer.create(bytesMarshallerFactory(), defaultSerializer) :
                 objectSerializer;
     }
 
diff --git a/src/test/java/net/openhft/chronicle/map/OSResizesMain.java b/src/test/java/net/openhft/chronicle/map/OSResizesMain.java
index ba9267316..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;
 
 /**
@@ -35,14 +32,16 @@ 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)
+        int valueSize = 1000 * 1000;
+        ChronicleMap<String, ByteArray> map = ChronicleMapBuilder.of(String.class, ByteArray.class)
                 .entrySize(50 * 1024 * 1024)
-                .entries(1000 * 1000)
+                .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();
@@ -77,3 +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