diff --git a/src/eva2/gui/GraphPointSetLegend.java b/src/eva2/gui/GraphPointSetLegend.java
index 5d074e02..a2db2313 100644
--- a/src/eva2/gui/GraphPointSetLegend.java
+++ b/src/eva2/gui/GraphPointSetLegend.java
@@ -17,6 +17,7 @@ import javax.swing.JLabel;
 import javax.swing.JPanel;
 
 import eva2.tools.Pair;
+import eva2.tools.StringTools;
 import eva2.tools.chart2d.SlimRect;
 
 /**
@@ -64,12 +65,12 @@ public class GraphPointSetLegend {
 		for (int i = 0; i < pointSetContainer.size(); i++) {
 			GraphPointSet pointset = pointSetContainer.get(i);
 			String entryStr;
-			if (appendIndex) entryStr = i + ": " + pointset.getInfoString();
+			if (appendIndex) entryStr = StringTools.expandPrefixZeros(i, pointSetContainer.size()-1) + ": " + pointset.getInfoString();
 			else entryStr = pointset.getInfoString();
 			legendEntries.add(new Pair<String, Color>(entryStr,pointset.getColor()));
 		}
 	}
-	
+
 	/**
 	 * A constructor without enumeration.
 	 * 
diff --git a/src/eva2/tools/StringTools.java b/src/eva2/tools/StringTools.java
index ae9a5613..fa365795 100644
--- a/src/eva2/tools/StringTools.java
+++ b/src/eva2/tools/StringTools.java
@@ -1,5 +1,6 @@
 package eva2.tools;
 
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
@@ -41,6 +42,26 @@ public class StringTools {
     	return (searchStringArray(arr, key, 0, ignoreCase))>=0; 
     }
     
+	/**
+	 * Convert an integer to a String filling it with zeros from the left, so
+	 * that is it of the same length as the Integer maxSize would achieve.
+	 * Note that this only works for positive values.
+	 * 
+	 * @param index
+	 * @param maxSize
+	 * @return
+	 */
+	public static String expandPrefixZeros(int index, int maxSize) {
+		if (maxSize<10) return ""+index;
+		else if (maxSize<100) return ((index<10) ? "0" : "")+index;
+		else {
+			int lenZeros = (int)Math.log10(maxSize)-(int)Math.log10(index);
+			char[] zerArr = new char[lenZeros];
+			Arrays.fill(zerArr, '0');
+			return new String(zerArr)+index;
+		} 
+	}
+
     /**
      * Search a String array for a given String and return its index if it is found.
      * If it is not found, -1 is returned.