diff --git a/crates/aiken-lang/src/ast.rs b/crates/aiken-lang/src/ast.rs
index 81acaa96..19cfc423 100644
--- a/crates/aiken-lang/src/ast.rs
+++ b/crates/aiken-lang/src/ast.rs
@@ -116,7 +116,7 @@ fn str_to_keyword(word: &str) -> Option<Token> {
         "type" => Some(Token::Type),
         "trace" => Some(Token::Trace),
         "test" => Some(Token::Test),
-        "error" => Some(Token::ErrorTerm),
+        "error" => Some(Token::Fail),
         "validator" => Some(Token::Validator),
         _ => None,
     }
diff --git a/crates/aiken-lang/src/expr.rs b/crates/aiken-lang/src/expr.rs
index 73bdf354..a5c43d98 100644
--- a/crates/aiken-lang/src/expr.rs
+++ b/crates/aiken-lang/src/expr.rs
@@ -552,7 +552,7 @@ impl UntypedExpr {
         }
     }
 
-    pub fn error(reason: Option<Self>, location: Span) -> Self {
+    pub fn fail(reason: Option<Self>, location: Span) -> Self {
         UntypedExpr::Trace {
             location,
             kind: TraceKind::Error,
diff --git a/crates/aiken-lang/src/format.rs b/crates/aiken-lang/src/format.rs
index 8193d135..353aa117 100644
--- a/crates/aiken-lang/src/format.rs
+++ b/crates/aiken-lang/src/format.rs
@@ -873,7 +873,7 @@ impl<'comments> Formatter<'comments> {
     ) -> Document<'a> {
         let (keyword, default_text) = match kind {
             TraceKind::Trace => ("trace", None),
-            TraceKind::Error => ("error", Some(DEFAULT_ERROR_STR.to_string())),
+            TraceKind::Error => ("fail", Some(DEFAULT_ERROR_STR.to_string())),
             TraceKind::Todo => ("todo", Some(DEFAULT_TODO_STR.to_string())),
         };
 
diff --git a/crates/aiken-lang/src/parser/expr/error_todo.rs b/crates/aiken-lang/src/parser/expr/fail_todo.rs
similarity index 89%
rename from crates/aiken-lang/src/parser/expr/error_todo.rs
rename to crates/aiken-lang/src/parser/expr/fail_todo.rs
index fe63483e..966b6f8d 100644
--- a/crates/aiken-lang/src/parser/expr/error_todo.rs
+++ b/crates/aiken-lang/src/parser/expr/fail_todo.rs
@@ -17,9 +17,9 @@ pub fn parser(
         just(Token::Todo)
             .ignore_then(message().or_not())
             .map_with_span(UntypedExpr::todo),
-        just(Token::ErrorTerm)
+        just(Token::Fail)
             .ignore_then(message().or_not())
-            .map_with_span(UntypedExpr::error),
+            .map_with_span(UntypedExpr::fail),
     ))
 }
 
@@ -31,7 +31,7 @@ mod tests {
     fn error_basic() {
         assert_expr!(
             r#"
-            error @"foo"
+            fail @"foo"
             "#
         );
     }
@@ -40,7 +40,7 @@ mod tests {
     fn error_sugar() {
         assert_expr!(
             r#"
-            error "foo"
+            fail "foo"
             "#
         );
     }
diff --git a/crates/aiken-lang/src/parser/expr/mod.rs b/crates/aiken-lang/src/parser/expr/mod.rs
index b0027e69..94ad489c 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 error_todo;
+mod fail_todo;
 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 error_todo::parser as error_todo;
+pub use fail_todo::parser as fail_todo;
 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((
-            error_todo(sequence.clone()),
+            fail_todo(sequence.clone()),
             pure_expression(sequence, expression),
         ))
     })
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 c7569fae..1f547cb1 100644
--- a/crates/aiken-lang/src/parser/expr/snapshots/error_basic.snap
+++ b/crates/aiken-lang/src/parser/expr/snapshots/error_basic.snap
@@ -1,15 +1,15 @@
 ---
-source: crates/aiken-lang/src/parser/expr/error_todo.rs
-description: "Code:\n\nerror @\"foo\"\n"
+source: crates/aiken-lang/src/parser/expr/fail_todo.rs
+description: "Code:\n\nfail @\"foo\"\n"
 ---
 Trace {
     kind: Error,
-    location: 0..12,
+    location: 0..11,
     then: ErrorTerm {
-        location: 0..12,
+        location: 0..11,
     },
     text: String {
-        location: 6..12,
+        location: 5..11,
         value: "foo",
     },
 }
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 a1ee2c84..aac19d17 100644
--- a/crates/aiken-lang/src/parser/expr/snapshots/error_sugar.snap
+++ b/crates/aiken-lang/src/parser/expr/snapshots/error_sugar.snap
@@ -1,15 +1,15 @@
 ---
-source: crates/aiken-lang/src/parser/expr/error_todo.rs
-description: "Code:\n\nerror \"foo\"\n"
+source: crates/aiken-lang/src/parser/expr/fail_todo.rs
+description: "Code:\n\nfail \"foo\"\n"
 ---
 Trace {
     kind: Error,
-    location: 0..11,
+    location: 0..10,
     then: ErrorTerm {
-        location: 0..11,
+        location: 0..10,
     },
     text: String {
-        location: 6..11,
+        location: 5..10,
         value: "foo",
     },
 }
diff --git a/crates/aiken-lang/src/parser/expr/when/clause.rs b/crates/aiken-lang/src/parser/expr/when/clause.rs
index 50a64114..6ac37655 100644
--- a/crates/aiken-lang/src/parser/expr/when/clause.rs
+++ b/crates/aiken-lang/src/parser/expr/when/clause.rs
@@ -63,7 +63,7 @@ mod tests {
         assert_expr!(
             r#"
             when val is {
-              Bar1{..} -> error
+              Bar1{..} -> fail
             }
             "#
         );
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 92b6171f..025955a4 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
@@ -1,16 +1,16 @@
 ---
 source: crates/aiken-lang/src/parser/expr/when/clause.rs
-description: "Code:\n\nwhen val is {\n  Bar1{..} -> error\n}\n"
+description: "Code:\n\nwhen val is {\n  Bar1{..} -> fail\n}\n"
 ---
 When {
-    location: 0..35,
+    location: 0..34,
     subject: Var {
         location: 5..8,
         name: "val",
     },
     clauses: [
         UntypedClause {
-            location: 16..33,
+            location: 16..32,
             patterns: [
                 Constructor {
                     is_record: true,
@@ -26,12 +26,12 @@ When {
             guard: None,
             then: Trace {
                 kind: Error,
-                location: 28..33,
+                location: 28..32,
                 then: ErrorTerm {
-                    location: 28..33,
+                    location: 28..32,
                 },
                 text: String {
-                    location: 28..33,
+                    location: 28..32,
                     value: "aiken::error",
                 },
             },
diff --git a/crates/aiken-lang/src/parser/lexer.rs b/crates/aiken-lang/src/parser/lexer.rs
index d196ce37..4940efa7 100644
--- a/crates/aiken-lang/src/parser/lexer.rs
+++ b/crates/aiken-lang/src/parser/lexer.rs
@@ -222,7 +222,9 @@ pub fn lexer() -> impl Parser<char, Vec<(Token, Span)>, Error = ParseError> {
 
     let keyword = text::ident().map(|s: String| match s.as_str() {
         "trace" => Token::Trace,
-        "error" => Token::ErrorTerm,
+        "fail" => Token::Fail,
+        // TODO: delete this eventually
+        "error" => Token::Fail,
         "as" => Token::As,
         "assert" => Token::Expect,
         "expect" => Token::Expect,
diff --git a/crates/aiken-lang/src/parser/token.rs b/crates/aiken-lang/src/parser/token.rs
index ddd92116..43b25f81 100644
--- a/crates/aiken-lang/src/parser/token.rs
+++ b/crates/aiken-lang/src/parser/token.rs
@@ -74,7 +74,7 @@ pub enum Token {
     Fn,
     If,
     Else,
-    ErrorTerm,
+    Fail,
     Expect,
     Is,
     Let,
@@ -170,7 +170,7 @@ impl fmt::Display for Token {
             Token::Trace => "trace",
             Token::Type => "type",
             Token::Test => "test",
-            Token::ErrorTerm => "error",
+            Token::Fail => "fail",
             Token::Validator => "validator",
         };
         write!(f, "\"{s}\"")
diff --git a/crates/aiken-lang/src/tests/format.rs b/crates/aiken-lang/src/tests/format.rs
index f37aa2cb..ad2955ee 100644
--- a/crates/aiken-lang/src/tests/format.rs
+++ b/crates/aiken-lang/src/tests/format.rs
@@ -247,7 +247,7 @@ fn test_format_nested_function_calls() {
             ,
             when output.datum is {
               InlineDatum(_) -> True
-              _ -> error "expected inline datum"
+              _ -> fail "expected inline datum"
             },
           ]
           |> list.and
@@ -271,13 +271,13 @@ fn test_format_trace_todo_error() {
         fn foo_3() {
           when x is {
             Foo -> True
-            _ -> error
+            _ -> fail
           }
         }
 
         fn foo_4() {
           if 14 == 42 {
-            error "I don't think so"
+            fail "I don't think so"
           } else {
             trace "been there"
             True
diff --git a/crates/aiken-lang/src/tests/snapshots/format_nested_function_calls.snap b/crates/aiken-lang/src/tests/snapshots/format_nested_function_calls.snap
index b072e1d0..d69f74c1 100644
--- a/crates/aiken-lang/src/tests/snapshots/format_nested_function_calls.snap
+++ b/crates/aiken-lang/src/tests/snapshots/format_nested_function_calls.snap
@@ -1,6 +1,6 @@
 ---
 source: crates/aiken-lang/src/tests/format.rs
-description: "Code:\n\nfn foo(output) {\n  [\n    output.address.stake_credential == Some(\n    Inline(\n    VerificationKeyCredential(\n      #\"66666666666666666666666666666666666666666666666666666666\",\n    ))\n    )\n    ,\n    when output.datum is {\n      InlineDatum(_) -> True\n      _ -> error \"expected inline datum\"\n    },\n  ]\n  |> list.and\n}\n"
+description: "Code:\n\nfn foo(output) {\n  [\n    output.address.stake_credential == Some(\n    Inline(\n    VerificationKeyCredential(\n      #\"66666666666666666666666666666666666666666666666666666666\",\n    ))\n    )\n    ,\n    when output.datum is {\n      InlineDatum(_) -> True\n      _ -> fail \"expected inline datum\"\n    },\n  ]\n  |> list.and\n}\n"
 ---
 fn foo(output) {
   [
@@ -13,7 +13,7 @@ fn foo(output) {
     ),
     when output.datum is {
       InlineDatum(_) -> True
-      _ -> error @"expected inline datum"
+      _ -> fail @"expected inline datum"
     },
   ]
     |> list.and
diff --git a/crates/aiken-lang/src/tests/snapshots/format_trace_todo_error.snap b/crates/aiken-lang/src/tests/snapshots/format_trace_todo_error.snap
index a41a4be8..ccf193c7 100644
--- a/crates/aiken-lang/src/tests/snapshots/format_trace_todo_error.snap
+++ b/crates/aiken-lang/src/tests/snapshots/format_trace_todo_error.snap
@@ -1,6 +1,6 @@
 ---
 source: crates/aiken-lang/src/tests/format.rs
-description: "Code:\n\nfn foo_1() {\n  todo\n}\n\nfn foo_2() {\n  todo \"my custom message\"\n}\n\nfn foo_3() {\n  when x is {\n    Foo -> True\n    _ -> error\n  }\n}\n\nfn foo_4() {\n  if 14 == 42 {\n    error \"I don't think so\"\n  } else {\n    trace \"been there\"\n    True\n  }\n}\n"
+description: "Code:\n\nfn foo_1() {\n  todo\n}\n\nfn foo_2() {\n  todo \"my custom message\"\n}\n\nfn foo_3() {\n  when x is {\n    Foo -> True\n    _ -> fail\n  }\n}\n\nfn foo_4() {\n  if 14 == 42 {\n    fail \"I don't think so\"\n  } else {\n    trace \"been there\"\n    True\n  }\n}\n"
 ---
 fn foo_1() {
   todo
@@ -13,13 +13,13 @@ fn foo_2() {
 fn foo_3() {
   when x is {
     Foo -> True
-    _ -> error
+    _ -> fail
   }
 }
 
 fn foo_4() {
   if 14 == 42 {
-    error @"I don't think so"
+    fail @"I don't think so"
   } else {
     trace @"been there"
     True
diff --git a/crates/aiken-project/src/tests/gen_uplc.rs b/crates/aiken-project/src/tests/gen_uplc.rs
index d58b28e9..a390b446 100644
--- a/crates/aiken-project/src/tests/gen_uplc.rs
+++ b/crates/aiken-project/src/tests/gen_uplc.rs
@@ -2601,7 +2601,7 @@ fn when_bool_is_true() {
           True ->
             True
           False ->
-            error
+            fail
         }
       }    
     "#;
@@ -2622,7 +2622,7 @@ fn when_bool_is_true_switched_cases() {
       test it() {
         when True is {
           False ->
-            error
+            fail
           True ->
             True
         }
@@ -2645,7 +2645,7 @@ fn when_bool_is_false() {
       test it() {
         when False is {
           False ->
-            error
+            fail
           True ->
             True
         }