diff --git a/prism/src/prism/LTSFromDA.java b/prism/src/prism/LTSFromDA.java
index e2601b28..7eb3011e 100644
--- a/prism/src/prism/LTSFromDA.java
+++ b/prism/src/prism/LTSFromDA.java
@@ -1,9 +1,35 @@
+//==============================================================================
+//	
+//	Copyright (c) 2002-
+//	Authors:
+// * Dave Parker <d.a.parker@cs.bham.ac.uk> (University of Birmingham/Oxford)
+//	
+//------------------------------------------------------------------------------
+//	
+//	This file is part of PRISM.
+//	
+//	PRISM is free software; you can redistribute it and/or modify
+//	it under the terms of the GNU General Public License as published by
+//	the Free Software Foundation; either version 2 of the License, or
+//	(at your option) any later version.
+//	
+//	PRISM is distributed in the hope that it will be useful,
+//	but WITHOUT ANY WARRANTY; without even the implied warranty of
+//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//	GNU General Public License for more details.
+//	
+//	You should have received a copy of the GNU General Public License
+//	along with PRISM; if not, write to the Free Software Foundation,
+//	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//	
+//==============================================================================
+
 package prism;
 
-import java.util.ArrayList;
 import java.util.BitSet;
+import java.util.HashSet;
 import java.util.Iterator;
-import java.util.List;
+import java.util.Set;
 
 import strat.MDStrategy;
 import explicit.LTS;
@@ -30,7 +56,7 @@ public class LTSFromDA extends ModelExplicit implements LTS
 	@Override
 	public Iterator<Integer> getSuccessorsIterator(int s)
 	{
-		List<Integer> succs = new ArrayList<Integer>();
+		Set<Integer> succs = new HashSet<Integer>();
 		int n = da.getNumEdges(s);
 		for (int i = 0; i < n; i++) {
 			succs.add(da.getEdgeDest(s, i));
@@ -185,7 +211,7 @@ public class LTSFromDA extends ModelExplicit implements LTS
 	@Override
 	public Iterator<Integer> getSuccessorsIterator(int s, int i)
 	{
-		List<Integer> succs = new ArrayList<Integer>();
+		Set<Integer> succs = new HashSet<Integer>();
 		succs.add(da.getEdgeDest(s, i));
 		return succs.iterator();
 	}