diff --git a/src/main/java/teetime/framework/AbstractStage.java b/src/main/java/teetime/framework/AbstractStage.java
index 42dd4f8add81e198da527d27e787c79c8359aa14..ad20973adae4bd1065369ffe1a57c71acd52ef46 100644
--- a/src/main/java/teetime/framework/AbstractStage.java
+++ b/src/main/java/teetime/framework/AbstractStage.java
@@ -28,8 +28,8 @@ import teetime.util.framework.port.PortList;
 import teetime.util.framework.port.PortRemovedListener;
 
 public abstract class AbstractStage extends Stage {
-	private final Map<Class<? extends ISignal>, Set<InputPort<?>>> signalMap = new HashMap<Class<? extends ISignal>, Set<InputPort<?>>>();
 
+	private final Map<Class<? extends ISignal>, Set<InputPort<?>>> signalMap = new HashMap<Class<? extends ISignal>, Set<InputPort<?>>>();
 	private final Set<Class<? extends ISignal>> triggeredSignalTypes = new HashSet<Class<? extends ISignal>>();
 
 	private final PortList<InputPort<?>> inputPorts = new PortList<InputPort<?>>();
diff --git a/src/main/java/teetime/stage/basic/merger/Merger.java b/src/main/java/teetime/stage/basic/merger/Merger.java
index 250f35d8bee12c1bfe368602f862d75905175577..1ed92585e37423346a2a4ee319f03d7872835c87 100644
--- a/src/main/java/teetime/stage/basic/merger/Merger.java
+++ b/src/main/java/teetime/stage/basic/merger/Merger.java
@@ -15,10 +15,7 @@
  */
 package teetime.stage.basic.merger;
 
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
-import java.util.Set;
 
 import teetime.framework.AbstractStage;
 import teetime.framework.InputPort;
@@ -41,7 +38,6 @@ import teetime.stage.basic.merger.strategy.RoundRobinStrategy;
  */
 public class Merger<T> extends AbstractStage {
 
-	private final Map<Class<? extends ISignal>, Set<InputPort<?>>> signalMap;
 	private final OutputPort<T> outputPort = this.createOutputPort();
 
 	private final IMergerStrategy strategy;
@@ -51,7 +47,6 @@ public class Merger<T> extends AbstractStage {
 	}
 
 	public Merger(final IMergerStrategy strategy) {
-		this.signalMap = new HashMap<Class<? extends ISignal>, Set<InputPort<?>>>();
 		this.strategy = strategy;
 		addInputPortRemovedListener(strategy);
 	}