diff --git a/lib/commons-bcel6-6.0-SNAPSHOT.jar b/lib/commons-bcel6-6.0-SNAPSHOT.jar
index d84ca41f..7bd71db2 100644
Binary files a/lib/commons-bcel6-6.0-SNAPSHOT.jar and b/lib/commons-bcel6-6.0-SNAPSHOT.jar differ
diff --git a/src/de/dhbwstuttgart/syntaxtree/operator/Operator.java b/src/de/dhbwstuttgart/syntaxtree/operator/Operator.java
index 7c6613f6..23ba6d0d 100755
--- a/src/de/dhbwstuttgart/syntaxtree/operator/Operator.java
+++ b/src/de/dhbwstuttgart/syntaxtree/operator/Operator.java
@@ -95,7 +95,9 @@ public abstract class Operator extends SyntaxTreeNode
 		}else if(returnType.equals("java.lang.Long")){
 			il.append(_cg.getInstructionFactory().createInvoke("java.lang.Long", "longValue", org.apache.commons.bcel6.generic.Type.LONG, new  org.apache.commons.bcel6.generic.Type[] {}, Constants.INVOKEVIRTUAL));
 		}else if(returnType.equals("java.lang.String")){
-			
+			throw new NotImplementedException(returnType);
+		}else if(returnType.equals("java.lang.Boolean")){
+			il.append(_cg.getInstructionFactory().createInvoke("java.lang.Boolean", "booleanValue", org.apache.commons.bcel6.generic.Type.BOOLEAN, new  org.apache.commons.bcel6.generic.Type[] {}, Constants.INVOKEVIRTUAL));
 		}else{
 			throw new NotImplementedException(returnType);
 		}