diff --git a/.settings/edu.umd.cs.findbugs.core.prefs b/.settings/edu.umd.cs.findbugs.core.prefs
index 6428bfcdf4bd941fab0b1cff6b8148f19fc75747..272829c98a168fe30809408fb54fba974a022f37 100644
--- a/.settings/edu.umd.cs.findbugs.core.prefs
+++ b/.settings/edu.umd.cs.findbugs.core.prefs
@@ -1,5 +1,5 @@
 #FindBugs User Preferences
-#Tue Nov 18 10:57:28 CET 2014
+#Tue Nov 25 12:10:00 CET 2014
 detector_threshold=3
 effort=max
 excludefilter0=.fbExcludeFilterFile|true
diff --git a/src/main/java/teetime/stage/basic/merger/Merger.java b/src/main/java/teetime/stage/basic/merger/Merger.java
index 59117bd596676201e1abcbcdc15f047e4d5f6b92..bde21d7f9c3028ca6fa093c4aab7e2f93ca67735 100644
--- a/src/main/java/teetime/stage/basic/merger/Merger.java
+++ b/src/main/java/teetime/stage/basic/merger/Merger.java
@@ -19,6 +19,7 @@ package teetime.stage.basic.merger;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 
 import teetime.framework.AbstractStage;
 import teetime.framework.InputPort;
@@ -43,7 +44,7 @@ public class Merger<T> extends AbstractStage {
 
 	private IMergerStrategy<T> strategy = new RoundRobinStrategy<T>();
 
-	private final Map<Class<?>, HashSet<InputPort<?>>> signalMap = new HashMap<Class<?>, HashSet<InputPort<?>>>();
+	private final Map<Class<?>, Set<InputPort<?>>> signalMap = new HashMap<Class<?>, Set<InputPort<?>>>();
 
 	@Override
 	public void executeWithPorts() {
@@ -71,7 +72,7 @@ public class Merger<T> extends AbstractStage {
 		this.logger.trace("Got signal: " + signal + " from input port: " + inputPort);
 
 		if (signalMap.containsKey(signal.getClass())) {
-			HashSet<InputPort<?>> set = signalMap.get(signal.getClass());
+			Set<InputPort<?>> set = signalMap.get(signal.getClass());
 			if (!set.add(inputPort)) {
 				this.logger.warn("Received more than one signal - " + signal + " - from input port: " + inputPort);
 			}
@@ -82,7 +83,7 @@ public class Merger<T> extends AbstractStage {
 			}
 		} else {
 			signal.trigger(this);
-			HashSet<InputPort<?>> tempSet = new HashSet<InputPort<?>>();
+			Set<InputPort<?>> tempSet = new HashSet<InputPort<?>>();
 			tempSet.add(inputPort);
 			signalMap.put(signal.getClass(), tempSet);
 		}