diff --git a/crates/aiken-lang/src/parser/expr/fail_todo.rs b/crates/aiken-lang/src/parser/expr/fail_todo.rs
index 5db5dd9d..f7e15251 100644
--- a/crates/aiken-lang/src/parser/expr/fail_todo.rs
+++ b/crates/aiken-lang/src/parser/expr/fail_todo.rs
@@ -1,25 +1,48 @@
 use chumsky::prelude::*;
 
 use crate::{
+    ast::TraceKind,
     expr::UntypedExpr,
     parser::{
         error::ParseError,
-        expr::{block::parser as block, string},
+        expr::{string, when::clause},
         token::Token,
     },
 };
 
-pub fn parser(
-    sequence: Recursive<'_, Token, UntypedExpr, ParseError>,
-) -> impl Parser<Token, UntypedExpr, Error = ParseError> + '_ {
-    let message = || choice((string::hybrid(), block(sequence.clone())));
+pub fn parser<'a>(
+    expression: Recursive<'a, Token, UntypedExpr, ParseError>,
+    sequence: Recursive<'a, Token, UntypedExpr, ParseError>,
+) -> impl Parser<Token, UntypedExpr, Error = ParseError> + 'a {
     choice((
-        just(Token::Todo)
-            .ignore_then(message().or_not())
-            .map_with_span(UntypedExpr::todo),
-        just(Token::Fail)
-            .ignore_then(message().or_not())
-            .map_with_span(UntypedExpr::fail),
+        just(Token::Todo).ignore_then(choice((
+            clause(expression.clone())
+                .ignored()
+                .rewind()
+                .map_with_span(|_, span| UntypedExpr::todo(None, span)),
+            choice((string::hybrid(), expression.clone()))
+                .or_not()
+                .map_with_span(UntypedExpr::todo),
+        ))),
+        just(Token::Fail).ignore_then(choice((
+            clause(expression.clone())
+                .ignored()
+                .rewind()
+                .map_with_span(|_, span| UntypedExpr::fail(None, span)),
+            choice((string::hybrid(), expression.clone()))
+                .or_not()
+                .map_with_span(UntypedExpr::fail),
+        ))),
+        just(Token::Trace)
+            .ignore_then(clause(expression.clone()).or_not().ignored().rewind())
+            .ignore_then(choice((string::hybrid(), expression.clone())))
+            .then(sequence.clone())
+            .map_with_span(|(text, then_), span| UntypedExpr::Trace {
+                kind: TraceKind::Trace,
+                location: span,
+                then: Box::new(then_),
+                text: Box::new(text),
+            }),
     ))
 }
 
@@ -71,4 +94,22 @@ mod tests {
             "#
         );
     }
+
+    #[test]
+    fn fail_empty() {
+        assert_expr!(
+            r#"
+            fail
+            "#
+        );
+    }
+
+    #[test]
+    fn trace_expr() {
+        assert_expr!(
+            r#"
+            trace some_var 
+            "#
+        );
+    }
 }
diff --git a/crates/aiken-lang/src/parser/expr/mod.rs b/crates/aiken-lang/src/parser/expr/mod.rs
index 94ad489c..dd291ec4 100644
--- a/crates/aiken-lang/src/parser/expr/mod.rs
+++ b/crates/aiken-lang/src/parser/expr/mod.rs
@@ -43,7 +43,7 @@ pub fn parser(
 ) -> impl Parser<Token, UntypedExpr, Error = ParseError> + '_ {
     recursive(|expression| {
         choice((
-            fail_todo(sequence.clone()),
+            fail_todo(expression.clone(), sequence.clone()),
             pure_expression(sequence, expression),
         ))
     })
diff --git a/crates/aiken-lang/src/parser/expr/sequence.rs b/crates/aiken-lang/src/parser/expr/sequence.rs
index 199d9902..7ad30044 100644
--- a/crates/aiken-lang/src/parser/expr/sequence.rs
+++ b/crates/aiken-lang/src/parser/expr/sequence.rs
@@ -13,15 +13,19 @@ use crate::{
 pub fn parser() -> impl Parser<Token, UntypedExpr, Error = ParseError> {
     recursive(|sequence| {
         choice((
-            just(Token::Trace)
-                .ignore_then(choice((string::hybrid(), block(sequence.clone()))))
-                .then(sequence.clone())
-                .map_with_span(|(text, then_), span| UntypedExpr::Trace {
-                    kind: TraceKind::Trace,
-                    location: span,
-                    then: Box::new(then_),
-                    text: Box::new(text),
-                }),
+            // just(Token::Trace)
+            //     .ignore_then(choice((
+            //         string::hybrid(),
+            //         block(sequence.clone()),
+            //         sequence.clone(),
+            //     )))
+            //     .then(sequence.clone())
+            //     .map_with_span(|(text, then_), span| UntypedExpr::Trace {
+            //         kind: TraceKind::Trace,
+            //         location: span,
+            //         then: Box::new(then_),
+            //         text: Box::new(text),
+            //     }),
             super::parser(sequence.clone())
                 .then(sequence.repeated())
                 .foldl(|current, next| current.append_in_sequence(next)),
diff --git a/crates/aiken-lang/src/tests/format.rs b/crates/aiken-lang/src/tests/format.rs
index 073deec0..92bf0d7a 100644
--- a/crates/aiken-lang/src/tests/format.rs
+++ b/crates/aiken-lang/src/tests/format.rs
@@ -581,3 +581,14 @@ fn format_int_uint() {
     "#
     );
 }
+
+#[test]
+fn fail_expr() {
+    assert_format!(
+        r#"
+        fn foo() {
+          fail some_var
+        }
+        "#
+    );
+}