diff --git a/crates/deno_task_shell/src/grammar.pest b/crates/deno_task_shell/src/grammar.pest
index 1a6d9a7..1481416 100644
--- a/crates/deno_task_shell/src/grammar.pest
+++ b/crates/deno_task_shell/src/grammar.pest
@@ -208,7 +208,6 @@ unary_arithmetic_expr = !{
 
 unary_pre_arithmetic_expr = !{
     (post_arithmetic_op | pre_arithmetic_op) ~ (parentheses_expr | VARIABLE | NUMBER)
-
 }
 
 unary_post_arithmetic_expr = !{
diff --git a/crates/deno_task_shell/src/parser.rs b/crates/deno_task_shell/src/parser.rs
index 026bb7b..a848bc1 100644
--- a/crates/deno_task_shell/src/parser.rs
+++ b/crates/deno_task_shell/src/parser.rs
@@ -426,11 +426,6 @@ pub enum ArithmeticPart {
     operator: BinaryOp,
     right: Box<ArithmeticPart>,
   },
-  #[error("Invalid unary arithmetic expression")]
-  UnaryArithmeticExpr {
-    operator: UnaryArithmeticOp,
-    operand: Box<ArithmeticPart>,
-  },
   #[error("Invalid pre arithmetic expression")]
   PreArithmeticExpr {
     operator: PreArithmeticOp,
@@ -486,21 +481,15 @@ pub enum AssignmentOp {
 #[cfg_attr(feature = "serialization", derive(serde::Serialize))]
 #[cfg_attr(feature = "serialization", serde(rename_all = "camelCase"))]
 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
-pub enum UnaryArithmeticOp {
+pub enum PreArithmeticOp {
+  Increment,  // ++
+  Decrement,  // --
   Plus,       // +
   Minus,      // -
   LogicalNot, // !
   BitwiseNot, // ~
 }
 
-#[cfg_attr(feature = "serialization", derive(serde::Serialize))]
-#[cfg_attr(feature = "serialization", serde(rename_all = "camelCase"))]
-#[derive(Debug, Clone, PartialEq, Eq, Copy)]
-pub enum PreArithmeticOp {
-  Increment, // ++
-  Decrement, // --
-}
-
 #[cfg_attr(feature = "serialization", derive(serde::Serialize))]
 #[cfg_attr(feature = "serialization", serde(rename_all = "camelCase"))]
 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
@@ -1470,16 +1459,16 @@ fn unary_pre_arithmetic_expr(pair: Pair<Rule>) -> Result<ArithmeticPart> {
 
   match first.as_rule() {
     Rule::pre_arithmetic_op => {
-      let op = parse_unary_arithmetic_op(first)?;
-      Ok(ArithmeticPart::UnaryArithmeticExpr {
-        operator: (op),
+      let op = parse_pre_arithmetic_op(first)?;
+      Ok(ArithmeticPart::PreArithmeticExpr {
+        operator: op,
         operand: (Box::new(operand)),
       })
     }
     Rule::post_arithmetic_op => {
       let op = parse_pre_arithmetic_op(first)?;
       Ok(ArithmeticPart::PreArithmeticExpr {
-        operator: (op),
+        operator: op,
         operand: (Box::new(operand)),
       })
     }
@@ -1514,29 +1503,11 @@ fn unary_post_arithmetic_expr(pair: Pair<Rule>) -> Result<ArithmeticPart> {
   }?;
   let op = parse_post_arithmetic_op(second)?;
   Ok(ArithmeticPart::PostArithmeticExpr {
-    operator: (op),
+    operator: op,
     operand: (Box::new(operand)),
   })
 }
 
-fn parse_unary_arithmetic_op(pair: Pair<Rule>) -> Result<UnaryArithmeticOp> {
-  let first = pair
-    .into_inner()
-    .next()
-    .ok_or_else(|| miette!("Expected unary operator"))?;
-
-  match first.as_rule() {
-    Rule::add => Ok(UnaryArithmeticOp::Plus),
-    Rule::subtract => Ok(UnaryArithmeticOp::Minus),
-    Rule::logical_not => Ok(UnaryArithmeticOp::LogicalNot),
-    Rule::bitwise_not => Ok(UnaryArithmeticOp::BitwiseNot),
-    _ => Err(miette!(
-      "Unexpected rule in unary arithmetic operator: {:?}",
-      first.as_rule()
-    )),
-  }
-}
-
 fn parse_pre_arithmetic_op(pair: Pair<Rule>) -> Result<PreArithmeticOp> {
   let first = pair
     .into_inner()
@@ -1545,6 +1516,10 @@ fn parse_pre_arithmetic_op(pair: Pair<Rule>) -> Result<PreArithmeticOp> {
   match first.as_rule() {
     Rule::increment => Ok(PreArithmeticOp::Increment),
     Rule::decrement => Ok(PreArithmeticOp::Decrement),
+    Rule::add => Ok(PreArithmeticOp::Plus),
+    Rule::subtract => Ok(PreArithmeticOp::Minus),
+    Rule::logical_not => Ok(PreArithmeticOp::LogicalNot),
+    Rule::bitwise_not => Ok(PreArithmeticOp::BitwiseNot),
     _ => Err(miette!(
       "Unexpected rule in post arithmetic operator: {:?}",
       first.as_rule()
diff --git a/crates/deno_task_shell/src/shell/execute.rs b/crates/deno_task_shell/src/shell/execute.rs
index bf00060..1ad4feb 100644
--- a/crates/deno_task_shell/src/shell/execute.rs
+++ b/crates/deno_task_shell/src/shell/execute.rs
@@ -52,7 +52,6 @@ use crate::parser::RedirectOp;
 use crate::parser::Sequence;
 use crate::parser::SequentialList;
 use crate::parser::SimpleCommand;
-use crate::parser::UnaryArithmeticOp;
 use crate::parser::Word;
 use crate::parser::WordPart;
 use crate::shell::types::WordEvalResult;
@@ -644,10 +643,6 @@ async fn evaluate_arithmetic_part(
       let rhs = Box::pin(evaluate_arithmetic_part(right, state)).await?;
       apply_conditional_binary_op(lhs, operator, rhs)
     }
-    ArithmeticPart::UnaryArithmeticExpr { operator, operand } => {
-      let val = Box::pin(evaluate_arithmetic_part(operand, state)).await?;
-      apply_unary_op(*operator, val)
-    }
     ArithmeticPart::PostArithmeticExpr { operand, operator } => {
       let val = Box::pin(evaluate_arithmetic_part(operand, state)).await?;
       apply_post_op(state, *operator, val, operand)
@@ -737,22 +732,6 @@ fn apply_conditional_binary_op(
   }
 }
 
-fn apply_unary_op(
-  op: UnaryArithmeticOp,
-  val: ArithmeticResult,
-) -> Result<ArithmeticResult, Error> {
-  match op {
-    UnaryArithmeticOp::Plus => Ok(val),
-    UnaryArithmeticOp::Minus => val.checked_neg(),
-    UnaryArithmeticOp::LogicalNot => Ok(if val.is_zero() {
-      ArithmeticResult::new(ArithmeticValue::Integer(1))
-    } else {
-      ArithmeticResult::new(ArithmeticValue::Integer(0))
-    }),
-    UnaryArithmeticOp::BitwiseNot => val.checked_not(),
-  }
-}
-
 fn apply_pre_op(
   state: &mut ShellState,
   op: PreArithmeticOp,
@@ -772,6 +751,9 @@ fn apply_pre_op(
       state.apply_changes(&result_clone.changes);
       Ok(result)
     }
+    _ => {
+      todo!("Pre arithmetic operator {:?} is not implemented", op)
+    }
   }
 }
 
diff --git a/crates/deno_task_shell/src/shell/types.rs b/crates/deno_task_shell/src/shell/types.rs
index bbfbb1f..92a484c 100644
--- a/crates/deno_task_shell/src/shell/types.rs
+++ b/crates/deno_task_shell/src/shell/types.rs
@@ -1044,45 +1044,6 @@ impl ArithmeticResult {
     })
   }
 
-  pub fn checked_neg(&self) -> Result<ArithmeticResult, Error> {
-    let result = match &self.value {
-      ArithmeticValue::Integer(val) => val
-        .checked_neg()
-        .map(ArithmeticValue::Integer)
-        .ok_or_else(|| anyhow::anyhow!("Integer overflow: -{}", val))?,
-      ArithmeticValue::Float(val) => {
-        let result = -val;
-        if result.is_finite() {
-          ArithmeticValue::Float(result)
-        } else {
-          return Err(anyhow::anyhow!("Float overflow: -{}", val));
-        }
-      }
-    };
-
-    Ok(ArithmeticResult {
-      value: result,
-      changes: self.changes.clone(),
-    })
-  }
-
-  pub fn checked_not(&self) -> Result<ArithmeticResult, Error> {
-    let result = match &self.value {
-      ArithmeticValue::Integer(val) => ArithmeticValue::Integer(!val),
-      ArithmeticValue::Float(_) => {
-        return Err(anyhow::anyhow!(
-          "Invalid arithmetic result type for bitwise NOT: {}",
-          self
-        ))
-      }
-    };
-
-    Ok(ArithmeticResult {
-      value: result,
-      changes: self.changes.clone(),
-    })
-  }
-
   pub fn checked_shl(
     &self,
     other: &ArithmeticResult,