diff --git a/crates/aiken-lang/src/parser/expr/fail_todo.rs b/crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
similarity index 81%
rename from crates/aiken-lang/src/parser/expr/fail_todo.rs
rename to crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
index f7e15251..61b8f2f8 100644
--- a/crates/aiken-lang/src/parser/expr/fail_todo.rs
+++ b/crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
@@ -34,13 +34,12 @@ pub fn parser<'a>(
                 .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())
+            .then(sequence.clone().or_not())
             .map_with_span(|(text, then_), span| UntypedExpr::Trace {
                 kind: TraceKind::Trace,
                 location: span,
-                then: Box::new(then_),
+                then: Box::new(then_.unwrap_or_else(|| UntypedExpr::todo(None, span))),
                 text: Box::new(text),
             }),
     ))
@@ -86,6 +85,24 @@ mod tests {
         );
     }
 
+    #[test]
+    fn todo_empty() {
+        assert_expr!(
+            r#"
+            todo
+            "#
+        );
+    }
+
+    #[test]
+    fn todo_expr() {
+        assert_expr!(
+            r#"
+            todo string.join(["foo", "bar"])
+            "#
+        );
+    }
+
     #[test]
     fn fail_expr() {
         assert_expr!(
@@ -106,6 +123,16 @@ mod tests {
 
     #[test]
     fn trace_expr() {
+        assert_expr!(
+            r#"
+            trace string.join(["foo", "bar"])
+            a
+            "#
+        );
+    }
+
+    #[test]
+    fn trace_expr_todo() {
         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 dd291ec4..91cf0ca2 100644
--- a/crates/aiken-lang/src/parser/expr/mod.rs
+++ b/crates/aiken-lang/src/parser/expr/mod.rs
@@ -7,7 +7,7 @@ pub mod assignment;
 mod block;
 pub(crate) mod bytearray;
 mod chained;
-mod fail_todo;
+mod fail_todo_trace;
 mod if_else;
 mod int;
 mod list;
@@ -23,7 +23,7 @@ pub use anonymous_function::parser as anonymous_function;
 pub use block::parser as block;
 pub use bytearray::parser as bytearray;
 pub use chained::parser as chained;
-pub use fail_todo::parser as fail_todo;
+pub use fail_todo_trace::parser as fail_todo_trace;
 pub use if_else::parser as if_else;
 pub use int::parser as int;
 pub use list::parser as list;
@@ -43,7 +43,7 @@ pub fn parser(
 ) -> impl Parser<Token, UntypedExpr, Error = ParseError> + '_ {
     recursive(|expression| {
         choice((
-            fail_todo(expression.clone(), sequence.clone()),
+            fail_todo_trace(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 7ad30044..1920bdc6 100644
--- a/crates/aiken-lang/src/parser/expr/sequence.rs
+++ b/crates/aiken-lang/src/parser/expr/sequence.rs
@@ -1,34 +1,14 @@
 use chumsky::prelude::*;
 
 use crate::{
-    ast::TraceKind,
     expr::UntypedExpr,
-    parser::{
-        error::ParseError,
-        expr::{block::parser as block, string},
-        token::Token,
-    },
+    parser::{error::ParseError, token::Token},
 };
 
 pub fn parser() -> impl Parser<Token, UntypedExpr, Error = ParseError> {
     recursive(|sequence| {
-        choice((
-            // 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)),
-        ))
+        super::parser(sequence.clone())
+            .then(sequence.repeated())
+            .foldl(|current, next| current.append_in_sequence(next))
     })
 }
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/error_basic.snap b/crates/aiken-lang/src/parser/expr/snapshots/error_basic.snap
index 1f547cb1..5efe3038 100644
--- a/crates/aiken-lang/src/parser/expr/snapshots/error_basic.snap
+++ b/crates/aiken-lang/src/parser/expr/snapshots/error_basic.snap
@@ -1,12 +1,12 @@
 ---
-source: crates/aiken-lang/src/parser/expr/fail_todo.rs
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
 description: "Code:\n\nfail @\"foo\"\n"
 ---
 Trace {
     kind: Error,
-    location: 0..11,
+    location: 5..11,
     then: ErrorTerm {
-        location: 0..11,
+        location: 5..11,
     },
     text: String {
         location: 5..11,
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/error_sugar.snap b/crates/aiken-lang/src/parser/expr/snapshots/error_sugar.snap
index aac19d17..5f5a60e4 100644
--- a/crates/aiken-lang/src/parser/expr/snapshots/error_sugar.snap
+++ b/crates/aiken-lang/src/parser/expr/snapshots/error_sugar.snap
@@ -1,12 +1,12 @@
 ---
-source: crates/aiken-lang/src/parser/expr/fail_todo.rs
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
 description: "Code:\n\nfail \"foo\"\n"
 ---
 Trace {
     kind: Error,
-    location: 0..10,
+    location: 5..10,
     then: ErrorTerm {
-        location: 0..10,
+        location: 5..10,
     },
     text: String {
         location: 5..10,
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/fail_empty.snap b/crates/aiken-lang/src/parser/expr/snapshots/fail_empty.snap
new file mode 100644
index 00000000..e99d8a88
--- /dev/null
+++ b/crates/aiken-lang/src/parser/expr/snapshots/fail_empty.snap
@@ -0,0 +1,15 @@
+---
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
+description: "Code:\n\nfail\n"
+---
+Trace {
+    kind: Error,
+    location: 1..2,
+    then: ErrorTerm {
+        location: 1..2,
+    },
+    text: String {
+        location: 1..2,
+        value: "aiken::error",
+    },
+}
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/fail_expr.snap b/crates/aiken-lang/src/parser/expr/snapshots/fail_expr.snap
index e91ac371..a7223e61 100644
--- a/crates/aiken-lang/src/parser/expr/snapshots/fail_expr.snap
+++ b/crates/aiken-lang/src/parser/expr/snapshots/fail_expr.snap
@@ -1,63 +1,54 @@
 ---
-source: crates/aiken-lang/src/parser/expr/fail_todo.rs
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
 description: "Code:\n\nfail str.join([@\"Some string \", some_params, @\" some string\"], @\"\")\n"
 ---
-Sequence {
-    location: 0..67,
-    expressions: [
-        Trace {
-            kind: Error,
-            location: 0..4,
-            then: ErrorTerm {
-                location: 0..4,
-            },
-            text: String {
-                location: 0..4,
-                value: "aiken::error",
-            },
-        },
-        Call {
-            arguments: [
-                CallArg {
-                    label: None,
+Trace {
+    kind: Error,
+    location: 5..67,
+    then: ErrorTerm {
+        location: 5..67,
+    },
+    text: Call {
+        arguments: [
+            CallArg {
+                label: None,
+                location: 14..61,
+                value: List {
                     location: 14..61,
-                    value: List {
-                        location: 14..61,
-                        elements: [
-                            String {
-                                location: 15..30,
-                                value: "Some string ",
-                            },
-                            Var {
-                                location: 32..43,
-                                name: "some_params",
-                            },
-                            String {
-                                location: 45..60,
-                                value: " some string",
-                            },
-                        ],
-                        tail: None,
-                    },
-                },
-                CallArg {
-                    label: None,
-                    location: 63..66,
-                    value: String {
-                        location: 63..66,
-                        value: "",
-                    },
-                },
-            ],
-            fun: FieldAccess {
-                location: 5..13,
-                label: "join",
-                container: Var {
-                    location: 5..8,
-                    name: "str",
+                    elements: [
+                        String {
+                            location: 15..30,
+                            value: "Some string ",
+                        },
+                        Var {
+                            location: 32..43,
+                            name: "some_params",
+                        },
+                        String {
+                            location: 45..60,
+                            value: " some string",
+                        },
+                    ],
+                    tail: None,
                 },
             },
-            location: 5..67,
+            CallArg {
+                label: None,
+                location: 63..66,
+                value: String {
+                    location: 63..66,
+                    value: "",
+                },
+            },
+        ],
+        fun: FieldAccess {
+            location: 5..13,
+            label: "join",
+            container: Var {
+                location: 5..8,
+                name: "str",
+            },
         },
-    ],
+        location: 5..67,
+    },
 }
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/todo_basic.snap b/crates/aiken-lang/src/parser/expr/snapshots/todo_basic.snap
index 92394c5d..201c08bf 100644
--- a/crates/aiken-lang/src/parser/expr/snapshots/todo_basic.snap
+++ b/crates/aiken-lang/src/parser/expr/snapshots/todo_basic.snap
@@ -1,12 +1,12 @@
 ---
-source: crates/aiken-lang/src/parser/expr/error_todo.rs
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
 description: "Code:\n\ntodo @\"foo\"\n"
 ---
 Trace {
     kind: Todo,
-    location: 0..11,
+    location: 5..11,
     then: ErrorTerm {
-        location: 0..11,
+        location: 5..11,
     },
     text: String {
         location: 5..11,
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/todo_empty.snap b/crates/aiken-lang/src/parser/expr/snapshots/todo_empty.snap
new file mode 100644
index 00000000..ae059379
--- /dev/null
+++ b/crates/aiken-lang/src/parser/expr/snapshots/todo_empty.snap
@@ -0,0 +1,15 @@
+---
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
+description: "Code:\n\ntodo\n"
+---
+Trace {
+    kind: Todo,
+    location: 1..2,
+    then: ErrorTerm {
+        location: 1..2,
+    },
+    text: String {
+        location: 1..2,
+        value: "aiken::todo",
+    },
+}
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/todo_expr.snap b/crates/aiken-lang/src/parser/expr/snapshots/todo_expr.snap
new file mode 100644
index 00000000..45117539
--- /dev/null
+++ b/crates/aiken-lang/src/parser/expr/snapshots/todo_expr.snap
@@ -0,0 +1,52 @@
+---
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
+description: "Code:\n\ntodo string.join([\"foo\", \"bar\"])\n"
+---
+Trace {
+    kind: Todo,
+    location: 5..32,
+    then: ErrorTerm {
+        location: 5..32,
+    },
+    text: Call {
+        arguments: [
+            CallArg {
+                label: None,
+                location: 17..31,
+                value: List {
+                    location: 17..31,
+                    elements: [
+                        ByteArray {
+                            location: 18..23,
+                            bytes: [
+                                102,
+                                111,
+                                111,
+                            ],
+                            preferred_format: Utf8String,
+                        },
+                        ByteArray {
+                            location: 25..30,
+                            bytes: [
+                                98,
+                                97,
+                                114,
+                            ],
+                            preferred_format: Utf8String,
+                        },
+                    ],
+                    tail: None,
+                },
+            },
+        ],
+        fun: FieldAccess {
+            location: 5..16,
+            label: "join",
+            container: Var {
+                location: 5..11,
+                name: "string",
+            },
+        },
+        location: 5..32,
+    },
+}
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/todo_sugar.snap b/crates/aiken-lang/src/parser/expr/snapshots/todo_sugar.snap
index ce2e4877..90e0777b 100644
--- a/crates/aiken-lang/src/parser/expr/snapshots/todo_sugar.snap
+++ b/crates/aiken-lang/src/parser/expr/snapshots/todo_sugar.snap
@@ -1,12 +1,12 @@
 ---
-source: crates/aiken-lang/src/parser/expr/error_todo.rs
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
 description: "Code:\n\ntodo \"foo\"\n"
 ---
 Trace {
     kind: Todo,
-    location: 0..10,
+    location: 5..10,
     then: ErrorTerm {
-        location: 0..10,
+        location: 5..10,
     },
     text: String {
         location: 5..10,
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/trace_expr.snap b/crates/aiken-lang/src/parser/expr/snapshots/trace_expr.snap
new file mode 100644
index 00000000..783fa6e1
--- /dev/null
+++ b/crates/aiken-lang/src/parser/expr/snapshots/trace_expr.snap
@@ -0,0 +1,53 @@
+---
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
+description: "Code:\n\ntrace string.join([\"foo\", \"bar\"])\na\n"
+---
+Trace {
+    kind: Trace,
+    location: 0..35,
+    then: Var {
+        location: 34..35,
+        name: "a",
+    },
+    text: Call {
+        arguments: [
+            CallArg {
+                label: None,
+                location: 18..32,
+                value: List {
+                    location: 18..32,
+                    elements: [
+                        ByteArray {
+                            location: 19..24,
+                            bytes: [
+                                102,
+                                111,
+                                111,
+                            ],
+                            preferred_format: Utf8String,
+                        },
+                        ByteArray {
+                            location: 26..31,
+                            bytes: [
+                                98,
+                                97,
+                                114,
+                            ],
+                            preferred_format: Utf8String,
+                        },
+                    ],
+                    tail: None,
+                },
+            },
+        ],
+        fun: FieldAccess {
+            location: 6..17,
+            label: "join",
+            container: Var {
+                location: 6..12,
+                name: "string",
+            },
+        },
+        location: 6..33,
+    },
+}
diff --git a/crates/aiken-lang/src/parser/expr/snapshots/trace_expr_todo.snap b/crates/aiken-lang/src/parser/expr/snapshots/trace_expr_todo.snap
new file mode 100644
index 00000000..c0ecd7ac
--- /dev/null
+++ b/crates/aiken-lang/src/parser/expr/snapshots/trace_expr_todo.snap
@@ -0,0 +1,23 @@
+---
+source: crates/aiken-lang/src/parser/expr/fail_todo_trace.rs
+description: "Code:\n\ntrace some_var \n"
+---
+Trace {
+    kind: Trace,
+    location: 0..14,
+    then: Trace {
+        kind: Todo,
+        location: 0..14,
+        then: ErrorTerm {
+            location: 0..14,
+        },
+        text: String {
+            location: 0..14,
+            value: "aiken::todo",
+        },
+    },
+    text: Var {
+        location: 6..14,
+        name: "some_var",
+    },
+}
diff --git a/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_double_todo.snap b/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_double_todo.snap
index b708e48a..0f9204ed 100644
--- a/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_double_todo.snap
+++ b/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_double_todo.snap
@@ -26,12 +26,12 @@ When {
             guard: None,
             then: Trace {
                 kind: Todo,
-                location: 28..32,
+                location: 35..39,
                 then: ErrorTerm {
-                    location: 28..32,
+                    location: 35..39,
                 },
                 text: String {
-                    location: 28..32,
+                    location: 35..39,
                     value: "aiken::todo",
                 },
             },
@@ -53,12 +53,12 @@ When {
             guard: None,
             then: Trace {
                 kind: Todo,
-                location: 47..51,
+                location: 52..53,
                 then: ErrorTerm {
-                    location: 47..51,
+                    location: 52..53,
                 },
                 text: String {
-                    location: 47..51,
+                    location: 52..53,
                     value: "aiken::todo",
                 },
             },
diff --git a/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_solo_error.snap b/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_solo_error.snap
index 025955a4..85e7ae46 100644
--- a/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_solo_error.snap
+++ b/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_solo_error.snap
@@ -26,12 +26,12 @@ When {
             guard: None,
             then: Trace {
                 kind: Error,
-                location: 28..32,
+                location: 33..34,
                 then: ErrorTerm {
-                    location: 28..32,
+                    location: 33..34,
                 },
                 text: String {
-                    location: 28..32,
+                    location: 33..34,
                     value: "aiken::error",
                 },
             },
diff --git a/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_todo.snap b/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_todo.snap
index 26c65eea..c0b59c19 100644
--- a/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_todo.snap
+++ b/crates/aiken-lang/src/parser/expr/when/snapshots/when_clause_todo.snap
@@ -46,9 +46,9 @@ When {
             guard: None,
             then: Trace {
                 kind: Todo,
-                location: 47..68,
+                location: 52..68,
                 then: ErrorTerm {
-                    location: 47..68,
+                    location: 52..68,
                 },
                 text: String {
                     location: 52..68,
diff --git a/crates/aiken-lang/src/tests/snapshots/fail_expr.snap b/crates/aiken-lang/src/tests/snapshots/fail_expr.snap
new file mode 100644
index 00000000..c2d4bfb4
--- /dev/null
+++ b/crates/aiken-lang/src/tests/snapshots/fail_expr.snap
@@ -0,0 +1,8 @@
+---
+source: crates/aiken-lang/src/tests/format.rs
+description: "Code:\n\nfn foo() {\n  fail some_var\n}\n"
+---
+fn foo() {
+  fail some_var
+}
+