diff --git a/crates/fuse-ast/src/ast.rs b/crates/fuse-ast/src/ast.rs
index 8798833..fa58b32 100644
--- a/crates/fuse-ast/src/ast.rs
+++ b/crates/fuse-ast/src/ast.rs
@@ -95,7 +95,8 @@ pub enum Expression {
     BooleanLiteral(Box<BooleanLiteral>),
     Identifier(Box<Identifier>),
     Function(Box<Function>),
-    If(Box<If>)
+    If(Box<If>),
+    UnaryOperator(Box<UnaryOperator>),
 }
 
 #[serializable]
@@ -218,10 +219,24 @@ pub struct If {
     pub r#else: Option<Else>,
 }
 
-
 #[serializable]
 #[derive(Debug, PartialEq)]
 pub enum Else {
     If(Box<If>),
     Block(Box<Block>),
 }
+
+#[serializable]
+#[derive(Debug, PartialEq)]
+pub struct UnaryOperator {
+    pub kind: UnaryOperatorKind,
+    pub expression: Expression,
+}
+
+#[serializable]
+#[derive(Debug, PartialEq)]
+pub enum UnaryOperatorKind {
+    Not(Span),
+    Minus(Span),
+    Plus(Span),
+}
diff --git a/crates/fuse-ast/src/ast_factory.rs b/crates/fuse-ast/src/ast_factory.rs
index 7120106..50ff4c7 100644
--- a/crates/fuse-ast/src/ast_factory.rs
+++ b/crates/fuse-ast/src/ast_factory.rs
@@ -121,4 +121,8 @@ impl AstFactory {
     pub fn if_expression(&self, expr: If) -> Expression {
         Expression::If(Box::from(expr))
     }
+
+    pub fn unary_operator_expression(&self, op: UnaryOperator) -> Expression {
+        Expression::UnaryOperator(Box::from(op))
+    }
 }