diff --git a/src/main/java/net/openhft/chronicle/hash/impl/stage/hash/Chaining.java b/src/main/java/net/openhft/chronicle/hash/impl/stage/hash/Chaining.java
index c44b8f640..d209736df 100644
--- a/src/main/java/net/openhft/chronicle/hash/impl/stage/hash/Chaining.java
+++ b/src/main/java/net/openhft/chronicle/hash/impl/stage/hash/Chaining.java
@@ -23,7 +23,7 @@ import java.util.List;
 import java.util.function.Function;
 
 @Staged
-public class Chaining extends ChainingInterface {
+public abstract class Chaining extends ChainingInterface {
 
     public final List<ChainingInterface> contextChain;
     public final int indexInContextChain;
diff --git a/src/main/java/net/openhft/chronicle/hash/impl/stage/hash/ThreadLocalState.java b/src/main/java/net/openhft/chronicle/hash/impl/stage/hash/ThreadLocalState.java
index 0478b0677..30da91ef0 100644
--- a/src/main/java/net/openhft/chronicle/hash/impl/stage/hash/ThreadLocalState.java
+++ b/src/main/java/net/openhft/chronicle/hash/impl/stage/hash/ThreadLocalState.java
@@ -16,6 +16,8 @@
 
 package net.openhft.chronicle.hash.impl.stage.hash;
 
-public class ThreadLocalState {
+public abstract class ThreadLocalState {
     public boolean iterationContextLockedInThisThread;
+
+    public abstract Thread owner();
 }
diff --git a/src/main/java/net/openhft/chronicle/map/impl/stage/map/ReplicatedChronicleMapHolderImpl.java b/src/main/java/net/openhft/chronicle/map/impl/stage/map/ReplicatedChronicleMapHolderImpl.java
index e9c77692c..fa2820e43 100644
--- a/src/main/java/net/openhft/chronicle/map/impl/stage/map/ReplicatedChronicleMapHolderImpl.java
+++ b/src/main/java/net/openhft/chronicle/map/impl/stage/map/ReplicatedChronicleMapHolderImpl.java
@@ -26,7 +26,7 @@ import net.openhft.chronicle.set.ChronicleSet;
 import net.openhft.sg.Staged;
 
 @Staged
-public class ReplicatedChronicleMapHolderImpl<K, V, R> extends Chaining
+public abstract class ReplicatedChronicleMapHolderImpl<K, V, R> extends Chaining
         implements ReplicatedChronicleMapHolder<K, V, R> {
 
     private final ReplicatedChronicleMap<K, V, R> m;
diff --git a/src/main/java/net/openhft/chronicle/map/impl/stage/map/VanillaChronicleMapHolderImpl.java b/src/main/java/net/openhft/chronicle/map/impl/stage/map/VanillaChronicleMapHolderImpl.java
index 29b0a5f4a..e2eda3b95 100644
--- a/src/main/java/net/openhft/chronicle/map/impl/stage/map/VanillaChronicleMapHolderImpl.java
+++ b/src/main/java/net/openhft/chronicle/map/impl/stage/map/VanillaChronicleMapHolderImpl.java
@@ -26,7 +26,7 @@ import net.openhft.chronicle.set.ChronicleSet;
 import net.openhft.sg.Staged;
 
 @Staged
-public class VanillaChronicleMapHolderImpl<K, V, R> extends Chaining
+public abstract class VanillaChronicleMapHolderImpl<K, V, R> extends Chaining
         implements VanillaChronicleMapHolder<K, V, R> {
     
     private final VanillaChronicleMap<K, V, R> m;