diff --git a/src/main/java/org/nustaq/serialization/FSTClazzInfo.java b/src/main/java/org/nustaq/serialization/FSTClazzInfo.java
index 69db1b94..dd1e0723 100644
--- a/src/main/java/org/nustaq/serialization/FSTClazzInfo.java
+++ b/src/main/java/org/nustaq/serialization/FSTClazzInfo.java
@@ -105,7 +105,7 @@ public void setDecoderAttached(Object decoderAttached) {
     boolean isAsciiNameShortString = false;
     boolean requiresInit = false;
     boolean hasTransient;
-    FSTObjectSerializer ser;
+    volatile FSTObjectSerializer ser;
     FSTFieldInfo fieldInfo[]; // serializable fields
 
     Class clazz;
@@ -975,19 +975,21 @@ public String getName() {
      * @return
      */
     public FSTObjectSerializer getSer() {
-        if (ser == null) {
+        FSTObjectSerializer serializer = ser;
+        if (serializer == null) {
             if (clazz == null) {
                 return null;
             }
-            ser = getSerNoStore();
-            if (ser == null) {
+            serializer = getSerNoStore();
+            if (serializer == null) {
                 ser = FSTSerializerRegistry.NULL;
+                return null;
             }
-        }
-        if (ser == FSTSerializerRegistry.NULL) {
+            ser = serializer;
+        } else if (serializer == FSTSerializerRegistry.NULL) {
             return null;
         }
-        return ser;
+        return serializer;
     }
 
     // no sideffecting lookup
diff --git a/src/main/java/org/nustaq/serialization/FSTObjectInput.java b/src/main/java/org/nustaq/serialization/FSTObjectInput.java
index d950e087..8b731ef3 100644
--- a/src/main/java/org/nustaq/serialization/FSTObjectInput.java
+++ b/src/main/java/org/nustaq/serialization/FSTObjectInput.java
@@ -997,6 +997,7 @@ public void close() throws IOException {
         closed = true;
         resetAndClearRefs();
         conf.returnObject(objects);
+        objects = null;
         getCodec().close();
     }
 
diff --git a/src/main/java/org/nustaq/serialization/FSTObjectOutput.java b/src/main/java/org/nustaq/serialization/FSTObjectOutput.java
index 66bfa806..b8095678 100644
--- a/src/main/java/org/nustaq/serialization/FSTObjectOutput.java
+++ b/src/main/java/org/nustaq/serialization/FSTObjectOutput.java
@@ -164,9 +164,10 @@ public void flush() throws IOException {
     public void close() throws IOException {
         flush();
         closed = true;
-        getCodec().close();
         resetAndClearRefs();
+        getCodec().close();
         conf.returnObject(objects);
+        objects = null;
     }
 
 
diff --git a/src/main/java/org/nustaq/serialization/FSTSerializerRegistry.java b/src/main/java/org/nustaq/serialization/FSTSerializerRegistry.java
index ee8ddc7c..14434119 100644
--- a/src/main/java/org/nustaq/serialization/FSTSerializerRegistry.java
+++ b/src/main/java/org/nustaq/serialization/FSTSerializerRegistry.java
@@ -31,7 +31,7 @@ public class FSTSerializerRegistry {
 
     private FSTSerializerRegistryDelegate delegate;
 
-    public static FSTObjectSerializer NULL = new NULLSerializer();
+    public static final FSTObjectSerializer NULL = new NULLSerializer();
 
     public void setDelegate(FSTSerializerRegistryDelegate delegate) {
         this.delegate = delegate;
diff --git a/src/main/java/org/nustaq/serialization/coders/FSTBytezDecoder.java b/src/main/java/org/nustaq/serialization/coders/FSTBytezDecoder.java
index fae1c484..c4641f95 100644
--- a/src/main/java/org/nustaq/serialization/coders/FSTBytezDecoder.java
+++ b/src/main/java/org/nustaq/serialization/coders/FSTBytezDecoder.java
@@ -387,6 +387,7 @@ public void registerClass(Class possible) {
     @Override
     public void close() {
         conf.returnObject(clnames);
+        clnames = null;
     }
 
     @Override
diff --git a/src/main/java/org/nustaq/serialization/coders/FSTBytezEncoder.java b/src/main/java/org/nustaq/serialization/coders/FSTBytezEncoder.java
index a0e5064d..9629ebb9 100644
--- a/src/main/java/org/nustaq/serialization/coders/FSTBytezEncoder.java
+++ b/src/main/java/org/nustaq/serialization/coders/FSTBytezEncoder.java
@@ -234,6 +234,7 @@ public int getWritten() {
     @Override
     public void close() throws IOException {
         conf.returnObject(clnames);
+        clnames = null;
     }
 
     @Override
diff --git a/src/main/java/org/nustaq/serialization/coders/FSTStreamDecoder.java b/src/main/java/org/nustaq/serialization/coders/FSTStreamDecoder.java
index 2b204024..d0b17b5c 100644
--- a/src/main/java/org/nustaq/serialization/coders/FSTStreamDecoder.java
+++ b/src/main/java/org/nustaq/serialization/coders/FSTStreamDecoder.java
@@ -493,6 +493,7 @@ public void registerClass(Class possible) {
     @Override
     public void close() {
         conf.returnObject(clnames);
+        clnames = null;
     }
 
     @Override
diff --git a/src/main/java/org/nustaq/serialization/coders/FSTStreamEncoder.java b/src/main/java/org/nustaq/serialization/coders/FSTStreamEncoder.java
index 3848c310..8b4dbdc7 100644
--- a/src/main/java/org/nustaq/serialization/coders/FSTStreamEncoder.java
+++ b/src/main/java/org/nustaq/serialization/coders/FSTStreamEncoder.java
@@ -475,7 +475,9 @@ public int getWritten() {
     @Override
     public void close() throws IOException {
         buffout.close();
+        clnames.clear();
         conf.returnObject(clnames);
+        clnames = null;
     }
 
     @Override