diff --git a/crates/lang/src/ast.rs b/crates/lang/src/ast.rs
index f839ca7a..ac9182ad 100644
--- a/crates/lang/src/ast.rs
+++ b/crates/lang/src/ast.rs
@@ -112,6 +112,46 @@ pub struct TypeAlias<T> {
 }
 
 pub type TypedDataType = DataType<Arc<Type>>;
+
+impl TypedDataType {
+    pub fn option(tipo: Arc<Type>) -> Self {
+        DataType {
+            constructors: vec![
+                RecordConstructor {
+                    location: Span::empty(),
+                    name: "Some".to_string(),
+                    arguments: vec![RecordConstructorArg {
+                        label: None,
+                        annotation: Annotation::Var {
+                            location: Span::empty(),
+                            name: "a".to_string(),
+                        },
+                        location: Span::empty(),
+                        tipo: tipo.clone(),
+                        doc: None,
+                    }],
+                    documentation: None,
+                    sugar: false,
+                },
+                RecordConstructor {
+                    location: Span::empty(),
+                    name: "None".to_string(),
+                    arguments: vec![],
+                    documentation: None,
+                    sugar: false,
+                },
+            ],
+            doc: None,
+            location: Span::empty(),
+            name: "Option".to_string(),
+            opaque: false,
+            parameters: vec!["a".to_string()],
+            public: true,
+            typed_parameters: vec![tipo],
+        }
+    }
+}
+
 pub type UntypedDataType = DataType<()>;
 
 #[derive(Debug, Clone, PartialEq)]
diff --git a/crates/project/src/lib.rs b/crates/project/src/lib.rs
index f9e2397f..eb45600d 100644
--- a/crates/project/src/lib.rs
+++ b/crates/project/src/lib.rs
@@ -8,10 +8,7 @@ pub mod script;
 pub mod telemetry;
 
 use aiken_lang::{
-    ast::{
-        Annotation, DataType, Definition, Function, ModuleKind, RecordConstructor,
-        RecordConstructorArg, Span, TypedDataType, TypedDefinition, TypedFunction,
-    },
+    ast::{Definition, Function, ModuleKind, TypedDataType, TypedDefinition, TypedFunction},
     builder::{DataTypeKey, FunctionAccessKey},
     builtins::{self, generic_var},
     tipo::TypeInfo,
@@ -418,7 +415,7 @@ where
         let mut imports = HashMap::new();
         let mut constants = HashMap::new();
 
-        let option_data_type = make_option();
+        let option_data_type = TypedDataType::option(generic_var(self.id_gen.next()));
 
         data_types.insert(
             DataTypeKey {
@@ -510,7 +507,7 @@ where
         let mut imports = HashMap::new();
         let mut constants = HashMap::new();
 
-        let option_data_type = make_option();
+        let option_data_type = TypedDataType::option(generic_var(self.id_gen.next()));
 
         data_types.insert(
             DataTypeKey {
@@ -826,40 +823,3 @@ fn is_aiken_path(path: &Path, dir: impl AsRef<Path>) -> bool {
             .expect("is_aiken_path(): to_str"),
     )
 }
-
-fn make_option() -> TypedDataType {
-    DataType {
-        constructors: vec![
-            RecordConstructor {
-                location: Span::empty(),
-                name: "Some".to_string(),
-                arguments: vec![RecordConstructorArg {
-                    label: None,
-                    annotation: Annotation::Var {
-                        location: Span::empty(),
-                        name: "a".to_string(),
-                    },
-                    location: Span::empty(),
-                    tipo: generic_var(0),
-                    doc: None,
-                }],
-                documentation: None,
-                sugar: false,
-            },
-            RecordConstructor {
-                location: Span::empty(),
-                name: "None".to_string(),
-                arguments: vec![],
-                documentation: None,
-                sugar: false,
-            },
-        ],
-        doc: None,
-        location: Span::empty(),
-        name: "Option".to_string(),
-        opaque: false,
-        parameters: vec!["a".to_string()],
-        public: true,
-        typed_parameters: vec![generic_var(0)],
-    }
-}