diff --git a/prism/src/explicit/rewards/MDPRewardsSimple.java b/prism/src/explicit/rewards/MDPRewardsSimple.java
index 0d5501da..afcdda24 100644
--- a/prism/src/explicit/rewards/MDPRewardsSimple.java
+++ b/prism/src/explicit/rewards/MDPRewardsSimple.java
@@ -76,7 +76,7 @@ public class MDPRewardsSimple implements MDPRewards
 	 */
 	public void addToStateReward(int s, double r)
 	{
-		setStateReward(s, stateRewards.get(s) + r);
+		setStateReward(s, getStateReward(s) + r);
 	}
 
 	/**