diff --git a/src/main/java/net/openhft/chronicle/map/AbstractChronicleMap.java b/src/main/java/net/openhft/chronicle/map/AbstractChronicleMap.java
index 7755c75ed..c4665bea3 100644
--- a/src/main/java/net/openhft/chronicle/map/AbstractChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/AbstractChronicleMap.java
@@ -25,6 +25,7 @@ import java.io.Serializable;
 import java.util.*;
 
 import static java.util.Collections.emptyList;
+import static net.openhft.chronicle.map.Objects.requireNonNull;
 
 abstract class AbstractChronicleMap<K, V> extends AbstractMap<K, V>
         implements ChronicleMap<K, V>, Serializable {
@@ -63,6 +64,7 @@ abstract class AbstractChronicleMap<K, V> extends AbstractMap<K, V>
 
     @Override
     public final V putIfAbsent(K key, V value) {
+        checkValue(value);
         try (MapKeyContext<V> c = context(key)) {
             // putIfAbsent() shouldn't actually put most of the time,
             // so check if the key is present under read lock first:
@@ -87,6 +89,8 @@ abstract class AbstractChronicleMap<K, V> extends AbstractMap<K, V>
         }
     }
 
+    abstract void checkValue(V value);
+
     @Override
     @SuppressWarnings("unchecked")
     public final V get(Object key) {
@@ -137,6 +141,7 @@ abstract class AbstractChronicleMap<K, V> extends AbstractMap<K, V>
 
     @Override
     public <R> R getMapped(K key, @NotNull Function<? super V, R> function) {
+        requireNonNull(function);
         try (MapKeyContext<V> c = context(key)) {
             return c.containsKey() ? function.apply(c.get()) : null;
         }
@@ -144,6 +149,7 @@ abstract class AbstractChronicleMap<K, V> extends AbstractMap<K, V>
 
     @Override
     public V putMapped(K key, @NotNull UnaryOperator<V> unaryOperator) {
+        requireNonNull(unaryOperator);
         try (MapKeyContext<V> c = context(key)) {
             // putMapped() should find a value, update & put most of the time,
             // so don't try to check key presence under read lock first,
@@ -193,6 +199,7 @@ abstract class AbstractChronicleMap<K, V> extends AbstractMap<K, V>
     public final boolean remove(Object key, Object value) {
         if (value == null)
             return false; // CHM compatibility; General ChronicleMap policy is to throw NPE
+        checkValue((V) value);
         try (MapKeyContext<V> c = context((K) key)) {
             // remove(key, value) should find the entry & remove most of the time,
             // so don't try to check key presence and value equivalence under read lock first,
@@ -204,6 +211,7 @@ abstract class AbstractChronicleMap<K, V> extends AbstractMap<K, V>
 
     @Override
     public final V replace(K key, V value) {
+        checkValue(value);
         try (MapKeyContext<V> c = context(key)) {
             // replace(key, value) should find the key & put the value most of the time,
             // so don't try to check key presence under read lock first,
@@ -223,6 +231,8 @@ abstract class AbstractChronicleMap<K, V> extends AbstractMap<K, V>
 
     @Override
     public final boolean replace(K key, V oldValue, V newValue) {
+        checkValue(oldValue);
+        checkValue(newValue);
         try (MapKeyContext<V> c = context(key)) {
             // replace(key, old, new) should find the entry & put new value most of the time,
             // so don't try to check key presence and value equivalence under read lock first,
diff --git a/src/main/java/net/openhft/chronicle/map/BytesChronicleMap.java b/src/main/java/net/openhft/chronicle/map/BytesChronicleMap.java
index 13f066f05..acb5a5ea6 100644
--- a/src/main/java/net/openhft/chronicle/map/BytesChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/BytesChronicleMap.java
@@ -70,6 +70,11 @@ public class BytesChronicleMap extends AbstractChronicleMap<Bytes, Bytes> {
         return context;
     }
 
+    @Override
+    void checkValue(Bytes value) {
+        Objects.requireNonNull(value);
+    }
+
     @Override
     public Class<Bytes> keyClass() {
         return Bytes.class;
diff --git a/src/main/java/net/openhft/chronicle/map/Objects.java b/src/main/java/net/openhft/chronicle/map/Objects.java
index f3058681c..6994c31dc 100644
--- a/src/main/java/net/openhft/chronicle/map/Objects.java
+++ b/src/main/java/net/openhft/chronicle/map/Objects.java
@@ -40,4 +40,9 @@ final class Objects {
                 o != null && builder.getClass() == o.getClass() &&
                         builder.toString().equals(o.toString());
     }
+
+    static void requireNonNull(Object obj) {
+        if (obj == null)
+            throw new NullPointerException();
+    }
 }
diff --git a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
index 112e86650..93bad7fa2 100755
--- a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
@@ -370,6 +370,7 @@ class VanillaChronicleMap<K, KI, MKI extends MetaBytesInterop<K, ? super KI>,
         }
     }
 
+    @Override
     final void checkValue(Object value) {
         if (vClass != Void.class && !vClass.isInstance(value)) {
             throw new ClassCastException("Value must be a " + vClass.getName() +