diff --git a/compiler/src/yul/mappers/expressions.rs b/compiler/src/yul/mappers/expressions.rs
index dccbd9cf99..b67f22c6d9 100644
--- a/compiler/src/yul/mappers/expressions.rs
+++ b/compiler/src/yul/mappers/expressions.rs
@@ -194,7 +194,6 @@ pub fn expr_comp_operation(context: &Context, exp: &Node<fe::Expr>) -> yul::Expr
                 true => expression! { iszero((slt([yul_left], [yul_right]))) },
                 false => expression! { iszero((lt([yul_left], [yul_right]))) },
             },
-            _ => unimplemented!(),
         };
     }
 
diff --git a/parser/src/ast.rs b/parser/src/ast.rs
index cd2e793edf..074aca4c9c 100644
--- a/parser/src/ast.rs
+++ b/parser/src/ast.rs
@@ -278,8 +278,4 @@ pub enum CompOperator {
     LtE,
     Gt,
     GtE,
-    Is,
-    IsNot,
-    In,
-    NotIn,
 }
diff --git a/parser/src/grammar/expressions.rs b/parser/src/grammar/expressions.rs
index 09b9ac1025..5afef419a9 100644
--- a/parser/src/grammar/expressions.rs
+++ b/parser/src/grammar/expressions.rs
@@ -199,9 +199,6 @@ fn infix_binding_power(op: TokenKind) -> Option<(u8, u8)> {
         // prefix Not => 65
 
         // all comparisons are the same
-        // In | NotIn => todo!("in, not in"), // conflicts with current `for` parsing impl
-        // TODO: `is not`
-        Is => (70, 71),
         Lt | LtEq | Gt | GtEq | NotEq | EqEq => (70, 71),
 
         Pipe => (80, 81),
@@ -356,8 +353,7 @@ fn infix_op(left: Node<Expr>, op: &Token, right: Node<Expr>) -> Node<Expr> {
             bin_op(left, op, right)
         }
 
-        In => todo!("in, not in"),
-        Is | Lt | LtEq | Gt | GtEq | NotEq | EqEq => comp_op(left, op, right),
+        Lt | LtEq | Gt | GtEq | NotEq | EqEq => comp_op(left, op, right),
 
         Dot => {
             let span = left.span + right.span;
@@ -458,7 +454,6 @@ fn comp_op(left: Node<Expr>, op: &Token, right: Node<Expr>) -> Node<Expr> {
     use TokenKind::*;
     let astop = match op.kind {
         In => todo!("in"), // CompOperator::In,
-        Is => CompOperator::Is,
         Lt => CompOperator::Lt,
         LtEq => CompOperator::LtE,
         Gt => CompOperator::Gt,
diff --git a/parser/src/lexer/token.rs b/parser/src/lexer/token.rs
index 1aa82b8309..adea67ae92 100644
--- a/parser/src/lexer/token.rs
+++ b/parser/src/lexer/token.rs
@@ -104,8 +104,6 @@ pub enum TokenKind {
     As,
     #[token("in")]
     In,
-    #[token("is")]
-    Is,
     #[token("not")]
     Not,
     #[token("or")]
@@ -246,7 +244,6 @@ impl TokenKind {
             And => "and",
             As => "as",
             In => "in",
-            Is => "is",
             Not => "not",
             Or => "or",
             ParenOpen => "(",