diff --git a/sources/zweic/Parser.scala b/sources/zweic/Parser.scala
index 7793d52..3596627 100755
--- a/sources/zweic/Parser.scala
+++ b/sources/zweic/Parser.scala
@@ -318,7 +318,7 @@
 	if ( token == ADD || token == SUB ) {
 		return Binop(sumOp(), left, sumExpression());
 	} else {
-		if ( token == OR ) {
+		if (check(OR)) {
 			return Unop(Operators.NOT,
 				Binop(Operators.AND,
 					Unop(Operators.NOT, left),
@@ -378,9 +378,12 @@
 		case NULLFACTOR => nextToken; rval = NullLit();
 		case READINT => nextToken; rval = ReadInt();
 		case READCHAR => nextToken; rval = ReadChar();
-		case LPAREN => nextToken; rval = expression(); accept(RPAREN);
+		case LPAREN => 
+		    nextToken; rval = expression(); 
+		    rval.brackets = true; accept(RPAREN);
 		case LACCOLADE => rval = block();
-		case NEW => nextToken; accept(IDENT); rval = New(Name(chars), params());
+		case NEW => nextToken; accept(IDENT); 
+		    rval = New(Name(chars), params());
 		case _ => error("Identifier, Number, String, 'true', 'false', 'this', 'null', 'readInt', 'readChar', '(Expression)', '{Block}' or 'new'");
 	}
 
diff --git a/sources/zweic/Printer.scala b/sources/zweic/Printer.scala
index f0d9aaf..f76db90 100755
--- a/sources/zweic/Printer.scala
+++ b/sources/zweic/Printer.scala
@@ -27,32 +27,34 @@
    */
   private var level = 0;
 
-  def joinprint(args:List[Tree], sep:String):Printer = args match {
+  def joinprint(args:List[Tree], sep: String):Printer = args match {
     case h :: Nil => 
       print(h);      
     case h :: t => 
-      print(h).print(sep);    
+      print(h).print(sep);
       joinprint(t, sep);      
     case Nil =>
       print("");
   }
-  //TODO: do this by passing a function as argument.
-  def joinprintln(args:List[Tree]):Printer = args match {
+
+  def joinprint(args:List[Tree]):Printer = args match {
     case h :: Nil => 
       print(h);      
     case h :: t => 
-      print(h);
-      println;
-      joinprintln(t);      
+      print(h).println;
+      joinprint(t);      
     case Nil =>
       print("");
   }
 
-
   /**
    * Prints a tree node.
    */
-  def print(tree: Tree): Printer = tree match {
+  def print(tree: Tree): Printer = {
+    if (tree.isInstanceOf[Expr] && tree.asInstanceOf[Expr].brackets)
+      print("(");
+   
+    tree match {
     case Program(decls, main) =>
       for (val d <- decls) {
         print(d).println;
@@ -70,7 +72,7 @@
 	case _ => null;
       }
       print(" {").indent.println;
-    joinprintln(members);
+    joinprint(members);
       undent.println.print("}").println;
 
     case FieldDecl(formal) =>
@@ -103,7 +105,7 @@
 
     case While(cond, stats) =>
       print("while (").print(cond).print(") {");
-      indent.println.joinprintln(stats).undent.println.print("}");
+      indent.println.joinprint(stats).undent.println.print("}");
 
     case Var(varname, vartype, init) =>
       print(vartype).print(" ").print(varname).print(" = ").
@@ -177,8 +179,13 @@
 
     case x => 
       error("unexpected error in tree");
-  }
-  
+    };
+
+    if (tree.isInstanceOf[Expr] && tree.asInstanceOf[Expr].brackets)
+      print(")");
+    
+    print("");
+  }  
 
   /**
    * Print abstract syntax trees separated by commas.
diff --git a/sources/zweic/Tree.scala b/sources/zweic/Tree.scala
index 758024d..cb83d99 100755
--- a/sources/zweic/Tree.scala
+++ b/sources/zweic/Tree.scala
@@ -104,7 +104,9 @@
 // Tree nodes for expressions
 
 /* A common superclass for expressions */
-abstract class Expr extends Tree;
+abstract class Expr extends Tree {
+  var brackets:Boolean = false;
+};
 
 /* E = Ident name */
 case class Ident(name: Name) extends Expr;