diff --git a/prism/src/explicit/Distribution.java b/prism/src/explicit/Distribution.java
index e9a45e8f..b47a474c 100644
--- a/prism/src/explicit/Distribution.java
+++ b/prism/src/explicit/Distribution.java
@@ -55,12 +55,19 @@ public class Distribution implements Iterable<Entry<Integer, Double>>
 	 * Copy constructor.
 	 */
 	public Distribution(Distribution distr)
+	{
+		this(distr.iterator());
+	}
+
+	/**
+	 * Construct a distribution from an iterator over transitions.
+	 */
+	public Distribution(Iterator<Entry<Integer, Double>> transitions)
 	{
 		this();
-		Iterator<Entry<Integer, Double>> i = distr.iterator();
-		while (i.hasNext()) {
-			Map.Entry<Integer, Double> e = i.next();
-			add(e.getKey(), e.getValue());
+		while (transitions.hasNext()) {
+			final Entry<Integer, Double> trans = transitions.next();
+			add(trans.getKey(), trans.getValue());
 		}
 	}