diff --git a/src/main/java/net/openhft/chronicle/map/ChronicleMap.java b/src/main/java/net/openhft/chronicle/map/ChronicleMap.java
index 115c598dc..8482ae791 100755
--- a/src/main/java/net/openhft/chronicle/map/ChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/ChronicleMap.java
@@ -197,17 +197,17 @@ public interface ChronicleMap<K, V> extends ConcurrentMap<K, V>, ChronicleHash {
      * @param <R>      return type.
      * @return the result of the function, or null if there is no entry for the key.
      */
-    <R> R mapForKey(K key, @NotNull Function<? super V, R> function);
+    <R> R getMapped(K key, @NotNull Function<? super V, R> function);
 
     /**
-     * Apply a mutator to the value for a key and return a result. A write lock is assumed. <p> If
+     * Apply a unaryOperator to the value for a key and return a result. A write lock is assumed. <p> If
      * there is no entry for this key null will be returned
      *
      * @param key     to apply the mapping to
-     * @param mutator to alter the value and calculate a result
+     * @param unaryOperator to alter the value and calculate a result
      * @return the result of the function.
      */
-    V putWith(K key, @NotNull Mutator<V> mutator);
+    V putMapped(K key, @NotNull UnaryOperator<V> unaryOperator);
 
     /**
      * exports all the entries to a {@link java.io.File} storing them in JSON format, an attempt is
diff --git a/src/main/java/net/openhft/chronicle/map/StatelessChronicleMap.java b/src/main/java/net/openhft/chronicle/map/StatelessChronicleMap.java
index e592fb2a9..727195d2a 100644
--- a/src/main/java/net/openhft/chronicle/map/StatelessChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/StatelessChronicleMap.java
@@ -123,7 +123,7 @@ class StatelessChronicleMap<K, V> implements ChronicleMap<K, V>, Closeable, Clon
         PUT_ALL_WITHOUT_ACC,
         HASH_CODE,
         MAP_FOR_KEY,
-        UPDATE_FOR_KEY
+        PUT_MAPPED
     }
 
 
@@ -482,7 +482,7 @@ class StatelessChronicleMap<K, V> implements ChronicleMap<K, V>, Closeable, Clon
     }
 
     @Nullable
-    public <R> R mapForKey(@Nullable K key, @NotNull Function<? super V, R> function) {
+    public <R> R getMapped(@Nullable K key, @NotNull Function<? super V, R> function) {
         if (key == null)
             throw keyNotNullNPE();
         return fetchObject(MAP_FOR_KEY, key, function);
@@ -491,10 +491,10 @@ class StatelessChronicleMap<K, V> implements ChronicleMap<K, V>, Closeable, Clon
 
     @Nullable
     @Override
-    public V putWith(@Nullable K key, @NotNull Mutator<V> mutator) {
+    public V putMapped(@Nullable K key, @NotNull UnaryOperator<V> unaryOperator) {
         if (key == null)
             throw keyNotNullNPE();
-        return fetchObject(UPDATE_FOR_KEY, key, mutator);
+        return fetchObject(PUT_MAPPED, key, unaryOperator);
     }
 
 
diff --git a/src/main/java/net/openhft/chronicle/map/TcpReplicator.java b/src/main/java/net/openhft/chronicle/map/TcpReplicator.java
index c4c82d6db..dbb480ba7 100644
--- a/src/main/java/net/openhft/chronicle/map/TcpReplicator.java
+++ b/src/main/java/net/openhft/chronicle/map/TcpReplicator.java
@@ -1417,8 +1417,8 @@ class StatelessServerConnector<K, V> {
             case MAP_FOR_KEY:
                 return mapForKey(reader, writer, sizeLocation);
 
-            case UPDATE_FOR_KEY:
-                return updateForKey(reader, writer, sizeLocation);
+            case PUT_MAPPED:
+                return putMapped(reader, writer, sizeLocation);
 
             default:
                 throw new IllegalStateException("unsupported event=" + event);
@@ -1430,7 +1430,7 @@ class StatelessServerConnector<K, V> {
         final K key = keyReaderWithSize.read(reader, null);
         final Function<V, ?> function = (Function<V, ?>) reader.readObject();
         try {
-            Object result = map.mapForKey(key, function);
+            Object result = map.getMapped(key, function);
             writer.writeObject(result);
         } catch (Throwable e) {
             LOG.info("", e);
@@ -1442,11 +1442,11 @@ class StatelessServerConnector<K, V> {
     }
 
     @Nullable
-    public Work updateForKey(@NotNull ByteBufferBytes reader, @NotNull Bytes writer, long sizeLocation) {
+    public Work putMapped(@NotNull ByteBufferBytes reader, @NotNull Bytes writer, long sizeLocation) {
         final K key = keyReaderWithSize.read(reader, null);
-        final Mutator<V> mutator = (Mutator<V>) reader.readObject();
+        final UnaryOperator<V> unaryOperator = (UnaryOperator<V>) reader.readObject();
         try {
-            Object result = map.putWith(key, mutator);
+            Object result = map.putMapped(key, unaryOperator);
             writer.writeObject(result);
         } catch (Throwable e) {
             LOG.info("", e);
diff --git a/src/main/java/net/openhft/chronicle/map/Mutator.java b/src/main/java/net/openhft/chronicle/map/UnaryOperator.java
similarity index 88%
rename from src/main/java/net/openhft/chronicle/map/Mutator.java
rename to src/main/java/net/openhft/chronicle/map/UnaryOperator.java
index 5d527604b..888eb4489 100755
--- a/src/main/java/net/openhft/chronicle/map/Mutator.java
+++ b/src/main/java/net/openhft/chronicle/map/UnaryOperator.java
@@ -11,7 +11,7 @@ import java.io.Serializable;
 
  */
 
-public interface Mutator<T> extends Serializable {
+public interface UnaryOperator<T> extends Serializable {
     /**
      * Applies this mutator to the given mutable argument.
      *
diff --git a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
index c55448db0..2864f578f 100755
--- a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
@@ -551,7 +551,7 @@ class VanillaChronicleMap<K, KI, MKI extends MetaBytesInterop<K, ? super KI>,
     }
 
     @Override
-    public <R> R mapForKey(K key, @NotNull Function<? super V, R> function) {
+    public <R> R getMapped(K key, @NotNull Function<? super V, R> function) {
         try (ReadContext<K, V> entry = lookupUsing(key, null,
                 false, false, LockType.READ_LOCK)) {
             return entry.present() ? function.apply(entry.value()) : null;
@@ -559,7 +559,7 @@ class VanillaChronicleMap<K, KI, MKI extends MetaBytesInterop<K, ? super KI>,
     }
 
     @Override
-    public  V putWith(K key, @NotNull Mutator<V> mutator) {
+    public  V putMapped(K key, @NotNull UnaryOperator<V> unaryOperator) {
 
 
         final V using = (vClass.equals(CharSequence.class)) ? (V) new StringBuilder() : null;
@@ -576,7 +576,7 @@ class VanillaChronicleMap<K, KI, MKI extends MetaBytesInterop<K, ? super KI>,
             if (entry.value() == null)
                 return null;
 
-            V result = mutator.update(entry.value());
+            V result = unaryOperator.update(entry.value());
             if (entry.value() instanceof StringBuilder) {
                 ((StringBuilder) using).setLength(0);
                 ((StringBuilder) using).append((CharSequence) result);
diff --git a/src/test/java/net/openhft/chronicle/map/CHMUseCasesTest.java b/src/test/java/net/openhft/chronicle/map/CHMUseCasesTest.java
index 838fa9d99..616357008 100644
--- a/src/test/java/net/openhft/chronicle/map/CHMUseCasesTest.java
+++ b/src/test/java/net/openhft/chronicle/map/CHMUseCasesTest.java
@@ -38,13 +38,13 @@ public class CHMUseCasesTest {
             map.put("Hello", "World");
             assertEquals("World", map.get("Hello"));
 
-            assertEquals("New World", map.mapForKey("Hello", new Function<String, String>() {
+            assertEquals("New World", map.getMapped("Hello", new Function<String, String>() {
                 @Override
                 public String apply(String s) {
                     return "New " + s;
                 }
             }));
-            assertEquals(null, map.mapForKey("No key", new Function<String, String>() {
+            assertEquals(null, map.getMapped("No key", new Function<String, String>() {
                 @Override
                 public String apply(String s) {
                     return "New " + s;
@@ -73,7 +73,7 @@ public class CHMUseCasesTest {
             map.put("Hello", "World");
 
 
-            map.putWith("Hello", new Mutator<String>() {
+            map.putMapped("Hello", new UnaryOperator<String>() {
                 @Override
                 public String update(String s) {
                     return "New " + s;
@@ -109,14 +109,14 @@ public class CHMUseCasesTest {
             assertNull(map.getUsing(key, value));
 
 
-            assertEquals("New World", map.mapForKey("Hello", new
+            assertEquals("New World", map.getMapped("Hello", new
                     Function<CharSequence, CharSequence>() {
                         @Override
                         public CharSequence apply(CharSequence s) {
                             return "New " + s;
                         }
                     }));
-            assertEquals(null, map.mapForKey("No key", new
+            assertEquals(null, map.getMapped("No key", new
                     Function<CharSequence, CharSequence>() {
                         @Override
                         public CharSequence apply(CharSequence s) {
@@ -124,8 +124,8 @@ public class CHMUseCasesTest {
                         }
                     }));
 
-            assertEquals("New World !!", map.putWith("Hello", new
-                    Mutator<CharSequence>() {
+            assertEquals("New World !!", map.putMapped("Hello", new
+                    UnaryOperator<CharSequence>() {
                         @Override
                         public CharSequence update(CharSequence s) {
                             ((StringBuilder) s).append(" !!");
@@ -135,8 +135,8 @@ public class CHMUseCasesTest {
 
             assertEquals("New World !!", map.get("Hello").toString());
 
-            assertEquals(null, map.putWith("no-key", new
-                    Mutator<CharSequence>() {
+            assertEquals(null, map.putMapped("no-key", new
+                    UnaryOperator<CharSequence>() {
                         @Override
                         public CharSequence update(CharSequence s) {
                             ((StringBuilder) s).append("!!");
@@ -268,13 +268,13 @@ public class CHMUseCasesTest {
             assertEquals(null, map.get(3));
             assertEquals(null, map.get(4));
 
-            assertEquals((Integer) 110, map.mapForKey(1, new Function<Integer, Integer>() {
+            assertEquals((Integer) 110, map.getMapped(1, new Function<Integer, Integer>() {
                 @Override
                 public Integer apply(Integer s) {
                     return 10 * s;
                 }
             }));
-            assertEquals(null, map.mapForKey(-1, new Function<Integer, Integer>() {
+            assertEquals(null, map.getMapped(-1, new Function<Integer, Integer>() {
                 @Override
                 public Integer apply(Integer s) {
                     return 10 * s;
@@ -282,7 +282,7 @@ public class CHMUseCasesTest {
             }));
 
             try {
-                map.putWith(1, new Mutator<Integer>() {
+                map.putMapped(1, new UnaryOperator<Integer>() {
                     @Override
                     public Integer update(Integer s) {
                         return s + 1;
@@ -311,13 +311,13 @@ public class CHMUseCasesTest {
             assertEquals(null, map.get(3L));
             assertEquals(null, map.get(4L));
 
-            assertEquals((Long) 110L, map.mapForKey(1L, new Function<Long, Long>() {
+            assertEquals((Long) 110L, map.getMapped(1L, new Function<Long, Long>() {
                 @Override
                 public Long apply(Long s) {
                     return 10 * s;
                 }
             }));
-            assertEquals(null, map.mapForKey(-1L, new Function<Long, Long>() {
+            assertEquals(null, map.getMapped(-1L, new Function<Long, Long>() {
                 @Override
                 public Long apply(Long s) {
                     return 10 * s;
@@ -325,7 +325,7 @@ public class CHMUseCasesTest {
             }));
 
             try {
-                map.putWith(1L, new Mutator<Long>() {
+                map.putMapped(1L, new UnaryOperator<Long>() {
                     @Override
                     public Long update(Long s) {
                         return s + 1;
@@ -354,13 +354,13 @@ public class CHMUseCasesTest {
             assertEquals(null, map.get(3.0));
             assertEquals(null, map.get(4.0));
 
-            assertEquals((Double) 110.0, map.mapForKey(1.0, new Function<Double, Double>() {
+            assertEquals((Double) 110.0, map.getMapped(1.0, new Function<Double, Double>() {
                 @Override
                 public Double apply(Double s) {
                     return 10 * s;
                 }
             }));
-            assertEquals(null, map.mapForKey(-1.0, new Function<Double, Double>() {
+            assertEquals(null, map.getMapped(-1.0, new Function<Double, Double>() {
                 @Override
                 public Double apply(Double s) {
                     return 10 * s;
@@ -368,7 +368,7 @@ public class CHMUseCasesTest {
             }));
 
             try {
-                map.putWith(1.0, new Mutator<Double>() {
+                map.putMapped(1.0, new UnaryOperator<Double>() {
                     @Override
                     public Double update(Double s) {
                         return s + 1;
@@ -401,20 +401,20 @@ public class CHMUseCasesTest {
             map.put(key1, value1);
 
 
-            assertTrue(Arrays.equals(new byte[]{11, 11}, map.mapForKey(key1, new Function<byte[], byte[]>() {
+            assertTrue(Arrays.equals(new byte[]{11, 11}, map.getMapped(key1, new Function<byte[], byte[]>() {
                 @Override
                 public byte[] apply(byte[] s) {
                     return Arrays.copyOf(s, 2);
                 }
             })));
-            assertEquals(null, map.mapForKey(key2, new Function<byte[], byte[]>() {
+            assertEquals(null, map.getMapped(key2, new Function<byte[], byte[]>() {
                 @Override
                 public byte[] apply(byte[] s) {
                     return Arrays.copyOf(s, 2);
                 }
             }));
 
-            assertTrue(Arrays.equals(new byte[]{12, 10}, map.putWith(key1, new Mutator<byte[]>() {
+            assertTrue(Arrays.equals(new byte[]{12, 10}, map.putMapped(key1, new UnaryOperator<byte[]>() {
                 @Override
                 public byte[] update(byte[] s) {
                     s[0]++;
@@ -458,10 +458,10 @@ public class CHMUseCasesTest {
             };
 
             map.put(key1, value1);
-            assertBBEquals(ByteBuffer.wrap(new byte[]{11, 11}), map.mapForKey(key1, function));
-            assertEquals(null, map.mapForKey(key2, function));
+            assertBBEquals(ByteBuffer.wrap(new byte[]{11, 11}), map.getMapped(key1, function));
+            assertEquals(null, map.getMapped(key2, function));
 
-            assertBBEquals(ByteBuffer.wrap(new byte[]{12, 10}), map.putWith(key1, new Mutator<ByteBuffer>() {
+            assertBBEquals(ByteBuffer.wrap(new byte[]{12, 10}), map.putMapped(key1, new UnaryOperator<ByteBuffer>() {
                 @Override
                 public ByteBuffer update(ByteBuffer s) {
                     s.put(0, (byte) (s.get(0) + 1));
@@ -568,10 +568,10 @@ public class CHMUseCasesTest {
                     return slice;
                 }
             };
-            assertBBEquals(ByteBuffer.wrap(new byte[]{11, 11}), map.mapForKey(key1, function));
-            assertEquals(null, map.mapForKey(key2, function));
+            assertBBEquals(ByteBuffer.wrap(new byte[]{11, 11}), map.getMapped(key1, function));
+            assertEquals(null, map.getMapped(key2, function));
 
-            assertBBEquals(ByteBuffer.wrap(new byte[]{12, 10}), map.putWith(key1, new Mutator<ByteBuffer>() {
+            assertBBEquals(ByteBuffer.wrap(new byte[]{12, 10}), map.putMapped(key1, new UnaryOperator<ByteBuffer>() {
                 @Override
                 public ByteBuffer update(ByteBuffer s) {
                     s.put(0, (byte) (s.get(0) + 1));
diff --git a/src/test/java/net/openhft/chronicle/map/ReplicationCheckingMap.java b/src/test/java/net/openhft/chronicle/map/ReplicationCheckingMap.java
index 757a728c5..41c314780 100644
--- a/src/test/java/net/openhft/chronicle/map/ReplicationCheckingMap.java
+++ b/src/test/java/net/openhft/chronicle/map/ReplicationCheckingMap.java
@@ -218,13 +218,13 @@ public class ReplicationCheckingMap<K, V> implements ChronicleMap<K, V> {
     }
 
     @Override
-    public <R> R mapForKey(K key, @NotNull Function<? super V, R> function) {
-        return map1.mapForKey(key, function);
+    public <R> R getMapped(K key, @NotNull Function<? super V, R> function) {
+        return map1.getMapped(key, function);
     }
 
     @Override
-    public V putWith(K key, @NotNull Mutator<V> mutator) {
-        return map1.putWith(key, mutator);
+    public V putMapped(K key, @NotNull UnaryOperator<V> unaryOperator) {
+        return map1.putMapped(key, unaryOperator);
     }
 
     @Override
diff --git a/src/test/java/net/openhft/chronicle/map/StatelessClientTest.java b/src/test/java/net/openhft/chronicle/map/StatelessClientTest.java
index c25fcfa6c..a169e7060 100644
--- a/src/test/java/net/openhft/chronicle/map/StatelessClientTest.java
+++ b/src/test/java/net/openhft/chronicle/map/StatelessClientTest.java
@@ -111,7 +111,7 @@ public class StatelessClientTest {
                     .class, StringBuilder.class)
                     .putReturnsNull(true)
                     .statelessClient(new InetSocketAddress("localhost", port)).create()) {
-                String actual = statelessMap.mapForKey(10, ToString.INSTANCE);
+                String actual = statelessMap.getMapped(10, ToString.INSTANCE);
 
                 assertEquals("Hello World", actual);
             }
@@ -131,7 +131,7 @@ public class StatelessClientTest {
             try (ChronicleMap<Integer, StringBuilder> statelessMap = ChronicleMapBuilder.of(Integer
                     .class, StringBuilder.class)
                     .statelessClient(new InetSocketAddress("localhost", port)).create()) {
-                String actual = statelessMap.mapForKey(11, ToString.INSTANCE);
+                String actual = statelessMap.getMapped(11, ToString.INSTANCE);
 
                 assertEquals(null, actual);
             }
diff --git a/src/test/java/net/openhft/chronicle/map/jrs166/map/StatelessChronicleMapTest.java b/src/test/java/net/openhft/chronicle/map/jrs166/map/StatelessChronicleMapTest.java
index 5d7a9551c..e4ddc060f 100755
--- a/src/test/java/net/openhft/chronicle/map/jrs166/map/StatelessChronicleMapTest.java
+++ b/src/test/java/net/openhft/chronicle/map/jrs166/map/StatelessChronicleMapTest.java
@@ -170,13 +170,13 @@ public class StatelessChronicleMapTest extends JSR166TestCase {
         }
 
         @Override
-        public <R> R mapForKey(K key, @NotNull Function<? super V, R> function) {
-            return d.mapForKey(key, function);
+        public <R> R getMapped(K key, @NotNull Function<? super V, R> function) {
+            return d.getMapped(key, function);
         }
 
         @Override
-        public  V putWith(K key, @NotNull Mutator<V> mutator) {
-            return d.putWith(key, mutator);
+        public  V putMapped(K key, @NotNull UnaryOperator<V> unaryOperator) {
+            return d.putMapped(key, unaryOperator);
         }
 
         @Override