diff --git a/java/com.sap.sse.operationaltransformation.test/src/com/sap/sse/operationaltransformation/test/OperationalTransformationTest.java b/java/com.sap.sse.operationaltransformation.test/src/com/sap/sse/operationaltransformation/test/OperationalTransformationTest.java
index b6da96b44bd..797eaaa953a 100755
--- a/java/com.sap.sse.operationaltransformation.test/src/com/sap/sse/operationaltransformation/test/OperationalTransformationTest.java
+++ b/java/com.sap.sse.operationaltransformation.test/src/com/sap/sse/operationaltransformation/test/OperationalTransformationTest.java
@@ -53,9 +53,9 @@ public class OperationalTransformationTest {
         }
     }
    
-    public static class StringInsertTransformer implements Transformer<StringInsertOperation> {
+    public static class StringInsertTransformer implements Transformer<StringState, StringInsertOperation> {
         @Override
-	public ClientServerOperationPair<StringInsertOperation> transform(StringInsertOperation clientOp, StringInsertOperation serverOp) {
+	public ClientServerOperationPair<StringState, StringInsertOperation> transform(StringInsertOperation clientOp, StringInsertOperation serverOp) {
 	    final StringInsertOperation resultClientOp;
 	    final StringInsertOperation resultServerOp;
 	    if (clientOp == null || serverOp == null) {
@@ -68,7 +68,7 @@ public class OperationalTransformationTest {
 		resultClientOp = clientOp;
 		resultServerOp = new StringInsertOperation(serverOp.getPos()+clientOp.getS().length(), serverOp.getS());
 	    }
-	    return new ClientServerOperationPair<StringInsertOperation>(resultClientOp, resultServerOp);
+	    return new ClientServerOperationPair<StringState, StringInsertOperation>(resultClientOp, resultServerOp);
 	}
     }
     
diff --git a/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/ClientServerOperationPair.java b/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/ClientServerOperationPair.java
index e3cb158947a..fa9182835ac 100755
--- a/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/ClientServerOperationPair.java
+++ b/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/ClientServerOperationPair.java
@@ -1,6 +1,6 @@
 package com.sap.sse.operationaltransformation;
 
-public class ClientServerOperationPair<O extends Operation<?>> {
+public class ClientServerOperationPair<S, O extends Operation<S>> {
     private O clientOp;
     private O serverOp;
 
diff --git a/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/OperationalTransformer.java b/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/OperationalTransformer.java
index 74099633359..8544c96b594 100755
--- a/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/OperationalTransformer.java
+++ b/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/OperationalTransformer.java
@@ -9,10 +9,10 @@ package com.sap.sse.operationaltransformation;
  * @param <S>
  * @param <O>
  */
-public class OperationalTransformer<S, O extends OperationWithTransformationSupport<S, O>> implements Transformer<O> {
+public class OperationalTransformer<S, O extends OperationWithTransformationSupport<S, O>> implements Transformer<S, O> {
     @Override
-    public ClientServerOperationPair<O> transform(O clientOp, O serverOp) {
-        ClientServerOperationPair<O> result = new ClientServerOperationPair<O>(
+    public ClientServerOperationPair<S, O> transform(O clientOp, O serverOp) {
+        ClientServerOperationPair<O> result = new ClientServerOperationPair<S, O>(
                 clientOp == null ? null : clientOp.transformClientOp(serverOp),
                         serverOp == null ? null : serverOp.transformServerOp(clientOp));
         return result;
diff --git a/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/PeerImpl.java b/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/PeerImpl.java
index 715dcc0a432..d5211d5ff27 100755
--- a/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/PeerImpl.java
+++ b/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/PeerImpl.java
@@ -53,21 +53,21 @@ public class PeerImpl<O extends Operation<S>, S> implements Peer<O, S> {
      */
     private final Map<Peer<O, S>, Integer> numberOfMergedOperations = new HashMap<Peer<O, S>, Integer>();
 
-    private final Transformer<O> transformer;
+    private final Transformer<S, O> transformer;
     
     /**
      * The background task handler which sends out the asynchronous updates to the peers.
      */
     private final ExecutorService merger;
 
-    public PeerImpl(Transformer<O> transformer, S initialState, Role role) {
+    public PeerImpl(Transformer<S, O> transformer, S initialState, Role role) {
 	this.transformer = transformer;
 	currentState = initialState;
 	this.role = role;
 	this.merger = Executors.newSingleThreadExecutor();
     }
     
-    public PeerImpl(String name, Transformer<O> transformer, S initialState, Role role) {
+    public PeerImpl(String name, Transformer<S, O> transformer, S initialState, Role role) {
 	this(transformer, initialState, role);
 	this.name = name;
     }
@@ -77,7 +77,7 @@ public class PeerImpl<O extends Operation<S>, S> implements Peer<O, S> {
      * the two-way link between client and server peers. The initial state is taken from
      * the server.
      */
-    public PeerImpl(Transformer<O> transformer, Peer<O, S> server) {
+    public PeerImpl(Transformer<S, O> transformer, Peer<O, S> server) {
 	this.transformer = transformer;
 	S initialState = server.addPeer(this);
         currentState = initialState;
@@ -91,7 +91,7 @@ public class PeerImpl<O extends Operation<S>, S> implements Peer<O, S> {
      * <tt>server</tt> peer, establishing the two-way link between client and
      * server peers. The initial state is taken from the server.
      */
-    public PeerImpl(String name, Transformer<O> transformer, Peer<O, S> server) {
+    public PeerImpl(String name, Transformer<S, O> transformer, Peer<O, S> server) {
 	this(transformer, server);
 	this.name = name;
     }
@@ -101,7 +101,7 @@ public class PeerImpl<O extends Operation<S>, S> implements Peer<O, S> {
 	merger.shutdown();
     }
 
-    private Transformer<O> getTransformer() {
+    private Transformer<S, O> getTransformer() {
         return transformer;
     }
     
@@ -154,7 +154,7 @@ public class PeerImpl<O extends Operation<S>, S> implements Peer<O, S> {
             for (O unconfirmedOperation : unmergedOperationsForSource
                     .getUnmergedOperations(numberOfOperationsSourceHasMergedFromThis)) {
                 if (role == Role.SERVER) {
-                    final ClientServerOperationPair<O> pair;
+                    final ClientServerOperationPair<S, O> pair;
                     if (transformedOp == null || unconfirmedOperation == null) {
                         pair = new ClientServerOperationPair<>(transformedOp, unconfirmedOperation);
                     } else {
@@ -163,7 +163,7 @@ public class PeerImpl<O extends Operation<S>, S> implements Peer<O, S> {
                     transformedOp = pair.getClientOp();
                     unmergedOperationsForSource.updateWithTransformed(localOpNumber, pair.getServerOp());
                 } else {
-                    final ClientServerOperationPair<O> pair;
+                    final ClientServerOperationPair<S, O> pair;
                     if (transformedOp == null || unconfirmedOperation == null) {
                         pair = new ClientServerOperationPair<>(unconfirmedOperation, transformedOp);
                     } else {
diff --git a/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/Transformer.java b/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/Transformer.java
index 764345898ec..331de2502b8 100755
--- a/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/Transformer.java
+++ b/java/com.sap.sse.operationaltransformation/src/com/sap/sse/operationaltransformation/Transformer.java
@@ -1,6 +1,6 @@
 package com.sap.sse.operationaltransformation;
 
-public interface Transformer<O extends Operation<?>> {
+public interface Transformer<S, O extends Operation<S>> {
     /**
      * Takes an operation from the client and an operation from the server, both based on the same state. The
      * complementary pair of operations is computed such that if the client applies the server operation returned, and
@@ -15,5 +15,5 @@ public interface Transformer<O extends Operation<?>> {
      * @param serverOp
      *            operation that was executed on the SERVER; never called with <code>null</code>
      */
-    ClientServerOperationPair<O> transform(O clientOp, O serverOp);
+    ClientServerOperationPair<S, O> transform(O clientOp, O serverOp);
 }