diff --git a/plugins/com.minres.scviewer.database.sqlite/src/com/minres/scviewer/database/sqlite/AbstractTxStream.java b/plugins/com.minres.scviewer.database.sqlite/src/com/minres/scviewer/database/sqlite/AbstractTxStream.java
index 2132faa..37d3c34 100644
--- a/plugins/com.minres.scviewer.database.sqlite/src/com/minres/scviewer/database/sqlite/AbstractTxStream.java
+++ b/plugins/com.minres.scviewer.database.sqlite/src/com/minres/scviewer/database/sqlite/AbstractTxStream.java
@@ -84,16 +84,7 @@ abstract class AbstractTxStream extends HierNode implements IWaveform {
 	}
 
 	private void putEvent(TxEvent ev){
-		Long time = ev.getTime();
-		if(events.containsKey(time)) {
-			IEvent[] oldV = events.get(time);
-			IEvent[] newV = new IEvent[oldV.length+1];
-			System.arraycopy(oldV, 0, newV, 0, oldV.length);
-			newV[oldV.length]=ev;
-			events.put(time, newV);
-		} else {
-			events.put(time, new IEvent[] {ev});
-		}
+		events.put(ev.getTime(), ev);
 	}
 
 	protected abstract Map<Integer, ITx> getTransactions();
diff --git a/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/AbstractTxStream.java b/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/AbstractTxStream.java
index 562de54..a5c98ac 100644
--- a/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/AbstractTxStream.java
+++ b/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/AbstractTxStream.java
@@ -73,14 +73,7 @@ abstract class AbstractTxStream extends HierNode implements IWaveform {
 	 * @param evt the evt
 	 */
 	public void addEvent(ITxEvent evt) {
-		if (!events.containsKey(evt.getTime()))
-			events.put(evt.getTime(), new IEvent[] { evt });
-		else {
-			IEvent[] evts = events.get(evt.getTime());
-			IEvent[] newEvts = Arrays.copyOf(evts, evts.length + 1);
-			newEvts[evts.length] = evt;
-			events.put(evt.getTime(), newEvts);
-		}
+		events.put(evt.getTime(), evt);
 	}
 
 	/**
diff --git a/plugins/com.minres.scviewer.database.vcd/src/com/minres/scviewer/database/vcd/VCDSignal.java b/plugins/com.minres.scviewer.database.vcd/src/com/minres/scviewer/database/vcd/VCDSignal.java
index 6bfd9fd..bb950f3 100644
--- a/plugins/com.minres.scviewer.database.vcd/src/com/minres/scviewer/database/vcd/VCDSignal.java
+++ b/plugins/com.minres.scviewer.database.vcd/src/com/minres/scviewer/database/vcd/VCDSignal.java
@@ -67,15 +67,7 @@ public class VCDSignal<T extends IEvent> extends HierNode implements IWaveform {
 	}
 
 	public void addSignalChange(Long time, T value){
-		if(values.containsKey(time)) {
-			IEvent[] oldV = values.get(time);
-			IEvent[] newV = new IEvent[oldV.length+1];
-			System.arraycopy(oldV, 0, newV, 0, oldV.length);
-			newV[oldV.length]=value;
-			values.put(time, newV);
-		} else {
-			values.put(time, new IEvent[] {value});
-		}
+		values.put(time, value);
 	}
 	
 	@Override
diff --git a/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/EventEntry.java b/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/EventEntry.java
index b719625..ac4f2f6 100644
--- a/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/EventEntry.java
+++ b/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/EventEntry.java
@@ -1,5 +1,7 @@
 package com.minres.scviewer.database;
 
+import java.util.Arrays;
+
 public class EventEntry implements Comparable<EventEntry>{
 	public long timestamp; // unsigned
 	public IEvent[] events = null;
@@ -25,4 +27,15 @@ public class EventEntry implements Comparable<EventEntry>{
 	public String toString() {
 		return String.format("e.%d@%d", events.length,timestamp);
 	}
+
+
+	public void append(IEvent value) {
+		if(events.length==0)
+			events = new IEvent[] {value};
+		else {
+			int idx = events.length;
+			events = Arrays.copyOf(events, idx+1);
+			events[idx]=value;
+		}
+	}
 }
diff --git a/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/EventList.java b/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/EventList.java
index 74cb340..84228fd 100644
--- a/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/EventList.java
+++ b/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/EventList.java
@@ -1,6 +1,7 @@
 package com.minres.scviewer.database;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 
@@ -85,24 +86,23 @@ public class EventList  implements IEventList {
 	}
 
 	@Override
-	public IEvent[] put(long key, IEvent[] value) {
+	public void put(long key, IEvent value) {
 		if(unmodifiable) throw new UnsupportedOperationException();
-		EventEntry e = new EventEntry(key, value);
 		if(store.size()==0 || store.get(store.size()-1).timestamp < key) {
-			store.add(e);
+			store.add(new EventEntry(key, new IEvent[] {value}));
 		} else {
 			int index = Collections.binarySearch(store, new EventEntry(key));
 	        // < 0 if element is not in the list, see Collections.binarySearch
 	        if (index < 0) {
+	    		EventEntry e = new EventEntry(key, new IEvent[] {value});
 	        	index = -(index + 1);
 		        store.add(index, e);
 	        } else { 
 	            // Insertion index is index of existing element, to add new element behind it increase index
-	        	store.set(index, e);
+	        	store.get(index).append(value);
 	        }
 		}
 		end=store.size();
-        return e.events;
 	}
 
 	@Override
diff --git a/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/IEventList.java b/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/IEventList.java
index ddc2459..7561c16 100644
--- a/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/IEventList.java
+++ b/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/IEventList.java
@@ -12,7 +12,7 @@ public interface IEventList extends Iterable<EventEntry> {
 
 	IEvent[] get(long key);
 
-	IEvent[] put(long key, IEvent[] value);
+	void put(long key, IEvent value);
 
 	long firstKey();
 
diff --git a/tests/com.minres.scviewer.database.test/src/com/minres/scviewer/database/test/EventListTest.java b/tests/com.minres.scviewer.database.test/src/com/minres/scviewer/database/test/EventListTest.java
index f82faa1..21db15f 100644
--- a/tests/com.minres.scviewer.database.test/src/com/minres/scviewer/database/test/EventListTest.java
+++ b/tests/com.minres.scviewer.database.test/src/com/minres/scviewer/database/test/EventListTest.java
@@ -12,7 +12,6 @@ import java.util.stream.Collectors;
 import org.junit.Test;
 
 import com.minres.scviewer.database.EventList;
-import com.minres.scviewer.database.IEvent;
 import com.minres.scviewer.database.IEventList;
 
 public class EventListTest {
@@ -20,7 +19,7 @@ public class EventListTest {
 	EventList createList(int[] times) {
 		EventList list = new EventList();
 		for(int time: times)
-			list.put(time, new IEvent[] {});
+			list.put(time, null);
 		return list;
 	}