diff --git a/prism/src/explicit/AccumulationProductSimple.java b/prism/src/explicit/AccumulationProductSimple.java
index bd91ab97..3c3ec84e 100644
--- a/prism/src/explicit/AccumulationProductSimple.java
+++ b/prism/src/explicit/AccumulationProductSimple.java
@@ -2,7 +2,6 @@ package explicit;
 
 import java.util.ArrayList;
 import java.util.BitSet;
-import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
 
@@ -82,7 +81,7 @@ public abstract class AccumulationProductSimple<M extends Model,Component> exten
                case ACCDIAPLUS:
             	   return constraintHolds(track,accexp,mc);
                default:
-                       throw new RuntimeException("Accumulation symbol cannot be handled...");
+                       throw new PrismException("Accumulation symbol cannot be handled by the simple transformation.");
                }
 	   }
 	
diff --git a/prism/src/explicit/AccumulationState.java b/prism/src/explicit/AccumulationState.java
index cd6d6739..0a0bb380 100644
--- a/prism/src/explicit/AccumulationState.java
+++ b/prism/src/explicit/AccumulationState.java
@@ -61,6 +61,7 @@ public class AccumulationState<Component> {
 		return Objects.hash(goodTracks, lastRestartNr, numberOfTracks, trackerId);
 	}
 
+	@SuppressWarnings("rawtypes")
 	@Override
 	public boolean equals(Object obj) {
 		if (this == obj)
diff --git a/prism/src/explicit/AccumulationTransformation.java b/prism/src/explicit/AccumulationTransformation.java
index a71ac457..684b5568 100644
--- a/prism/src/explicit/AccumulationTransformation.java
+++ b/prism/src/explicit/AccumulationTransformation.java
@@ -98,6 +98,7 @@ public class AccumulationTransformation<M extends Model> implements ModelExpress
 		}
 	}
 
+	@SuppressWarnings("unchecked")
 	protected void doTransformationComplex(ExpressionAccumulation accexp, Vector<Rewards> rewards) throws PrismException {
 		// Build the product
 		if(accexp.hasRegularExpression()) {
@@ -140,6 +141,7 @@ public class AccumulationTransformation<M extends Model> implements ModelExpress
 		}
 	}	
 	
+	@SuppressWarnings("unchecked")
 	protected void doTransformationSimple(ExpressionAccumulation accexp, Vector<Rewards> rewards) throws PrismException {
 		// Build the product
 		if(accexp.hasRegularExpression()) {