diff --git a/sources/zweic/Parser.scala b/sources/zweic/Parser.scala
index 3596627..0105d34 100755
--- a/sources/zweic/Parser.scala
+++ b/sources/zweic/Parser.scala
@@ -318,13 +318,15 @@
 	if ( token == ADD || token == SUB ) {
 		return Binop(sumOp(), left, sumExpression());
 	} else {
-		if (check(OR)) {
-			return Unop(Operators.NOT,
-				Binop(Operators.AND,
-					Unop(Operators.NOT, left),
-					Unop(Operators.NOT, sumExpression())
-					)
-				);
+		if (check(OR)) {	
+		  var right = sumExpression();
+		  left.brackets = true;
+		  right.brackets = true;
+		  var bol = Unop(Operators.NOT, left);
+		  var bor = Unop(Operators.NOT, right);
+		  var bo = Binop(Operators.AND, bol, bor);
+		  bo.brackets = true;
+		  return Unop(Operators.NOT, bo);
 		} else {
 			return left;
 		}