diff --git a/src/main/java/abstractSyntaxTree/Expression/UnaryExpression.java b/src/main/java/abstractSyntaxTree/Expression/UnaryExpression.java
index 4a2243c..21b130d 100644
--- a/src/main/java/abstractSyntaxTree/Expression/UnaryExpression.java
+++ b/src/main/java/abstractSyntaxTree/Expression/UnaryExpression.java
@@ -15,8 +15,8 @@ import java.util.Objects;
 
 public class UnaryExpression extends AbstractType implements IExpression{
     public String operator;
-    public IDatatype operand;
-    public UnaryExpression(String operator, IDatatype operand){
+    public IExpression operand;
+    public UnaryExpression(String operator, IExpression operand){
         this.operator = operator;
         this.operand = operand;
     }
diff --git a/src/main/java/astGenerator/ASTGenerator.java b/src/main/java/astGenerator/ASTGenerator.java
index 3d7d34e..980fc01 100644
--- a/src/main/java/astGenerator/ASTGenerator.java
+++ b/src/main/java/astGenerator/ASTGenerator.java
@@ -271,7 +271,8 @@ public class ASTGenerator extends DecafBaseVisitor<Node> {
         } else if (ctx.value() != null) {
             return visitValue(ctx.value());
         } else if (ctx.binaryExpr() != null) {
-            //todo
+            IExpression expression = (IExpression) visit(ctx.binaryExpr());
+            return new UnaryExpression("!", expression);
         }
         return null;
     }