diff --git a/nac3core/src/codegen/expr.rs b/nac3core/src/codegen/expr.rs
index e0f72ba84..8e629f9b0 100644
--- a/nac3core/src/codegen/expr.rs
+++ b/nac3core/src/codegen/expr.rs
@@ -13,7 +13,7 @@ impl<'ctx> CodeGenContext<'ctx> {
             // we cannot have other types, virtual type should be handled by function calls
             _ => unreachable!(),
         };
-        let def = &self.top_level.definitions.read()[obj_id];
+        let def = &self.top_level.definitions.read()[obj_id.0];
         let index = if let TopLevelDef::Class { fields, .. } = &*def.read() {
             fields.iter().find_position(|x| x.0 == attr).unwrap().0
         } else {
@@ -137,7 +137,7 @@ impl<'ctx> CodeGenContext<'ctx> {
         let primitives = &self.top_level.primitives;
         match &expr.node {
             ExprKind::Constant { value, .. } => {
-                let ty = expr.custom.clone().unwrap();
+                let ty = expr.custom.unwrap();
                 self.gen_const(value, ty)
             }
             ExprKind::Name { id, .. } => {
diff --git a/nac3core/src/top_level.rs b/nac3core/src/top_level.rs
index 87d823639..a861e7913 100644
--- a/nac3core/src/top_level.rs
+++ b/nac3core/src/top_level.rs
@@ -7,12 +7,13 @@ use inkwell::{builder::Builder, context::Context, module::Module, values::Pointe
 use parking_lot::RwLock;
 use rustpython_parser::ast::Stmt;
 
-pub struct DefinitionId(usize);
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy)]
+pub struct DefinitionId(pub usize);
 
 pub enum TopLevelDef {
     Class {
         // object ID used for TypeEnum
-        object_id: usize,
+        object_id: DefinitionId,
         // type variables bounded to the class.
         type_vars: Vec<Type>,
         // class fields and method signature.
diff --git a/nac3core/src/typecheck/magic_methods.rs b/nac3core/src/typecheck/magic_methods.rs
index 4c6486990..ff28da5ed 100644
--- a/nac3core/src/typecheck/magic_methods.rs
+++ b/nac3core/src/typecheck/magic_methods.rs
@@ -61,7 +61,7 @@ pub fn comparison_name(op: &Cmpop) -> Option<&'static str> {
     }
 }
 
-pub fn impl_binop(unifier: &mut Unifier, store: &PrimitiveStore, ty: Type, other_ty: &[Type], ret_ty: Type, ops: &[ast::Operator]) {
+pub fn impl_binop(unifier: &mut Unifier, _store: &PrimitiveStore, ty: Type, other_ty: &[Type], ret_ty: Type, ops: &[ast::Operator]) {
     if let TypeEnum::TObj {fields, ..} = unifier.get_ty(ty).borrow() {
         for op in ops {
             fields.borrow_mut().insert(
diff --git a/nac3core/src/typecheck/type_inferencer/test.rs b/nac3core/src/typecheck/type_inferencer/test.rs
index 4592ec6ef..d88fe6d46 100644
--- a/nac3core/src/typecheck/type_inferencer/test.rs
+++ b/nac3core/src/typecheck/type_inferencer/test.rs
@@ -55,27 +55,27 @@ impl TestEnvironment {
         let mut unifier = Unifier::new();
 
         let int32 = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 0,
+            obj_id: DefinitionId(0),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
         let int64 = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 1,
+            obj_id: DefinitionId(1),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
         let float = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 2,
+            obj_id: DefinitionId(2),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
         let bool = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 3,
+            obj_id: DefinitionId(3),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
         let none = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 4,
+            obj_id: DefinitionId(4),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
@@ -120,27 +120,27 @@ impl TestEnvironment {
         let mut unifier = Unifier::new();
         let mut identifier_mapping = HashMap::new();
         let int32 = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 0,
+            obj_id: DefinitionId(0),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
         let int64 = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 1,
+            obj_id: DefinitionId(1),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
         let float = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 2,
+            obj_id: DefinitionId(2),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
         let bool = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 3,
+            obj_id: DefinitionId(3),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
         let none = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 4,
+            obj_id: DefinitionId(4),
             fields: HashMap::new().into(),
             params: HashMap::new(),
         });
@@ -151,7 +151,7 @@ impl TestEnvironment {
         let (v0, id) = unifier.get_fresh_var();
 
         let foo_ty = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 5,
+            obj_id: DefinitionId(5),
             fields: [("a".into(), v0)].iter().cloned().collect::<HashMap<_, _>>().into(),
             params: [(id, v0)].iter().cloned().collect(),
         });
@@ -171,7 +171,7 @@ impl TestEnvironment {
             vars: Default::default(),
         }));
         let bar = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 6,
+            obj_id: DefinitionId(6),
             fields: [("a".into(), int32), ("b".into(), fun)]
                 .iter()
                 .cloned()
@@ -189,7 +189,7 @@ impl TestEnvironment {
         );
 
         let bar2 = unifier.add_ty(TypeEnum::TObj {
-            obj_id: 7,
+            obj_id: DefinitionId(7),
             fields: [("a".into(), bool), ("b".into(), fun)]
                 .iter()
                 .cloned()
diff --git a/nac3core/src/typecheck/typedef/mod.rs b/nac3core/src/typecheck/typedef/mod.rs
index 93d90bf0c..daf7fcfe7 100644
--- a/nac3core/src/typecheck/typedef/mod.rs
+++ b/nac3core/src/typecheck/typedef/mod.rs
@@ -6,6 +6,7 @@ use std::iter::once;
 use std::rc::Rc;
 use std::sync::{Arc, Mutex};
 
+use crate::top_level::DefinitionId;
 use super::unification_table::{UnificationKey, UnificationTable};
 
 #[cfg(test)]
@@ -64,7 +65,7 @@ pub enum TypeEnum {
         ty: Type,
     },
     TObj {
-        obj_id: usize,
+        obj_id: DefinitionId,
         fields: RefCell<Mapping<String>>,
         params: VarMap,
     },
@@ -433,7 +434,7 @@ impl Unifier {
                 TObj { obj_id: id2, params: params2, .. },
             ) => {
                 if id1 != id2 {
-                    return Err(format!("Cannot unify objects with ID {} and {}", id1, id2));
+                    return Err(format!("Cannot unify objects with ID {} and {}", id1.0, id2.0));
                 }
                 for (x, y) in zip(params1.values(), params2.values()) {
                     self.unify(*x, *y)?;
@@ -570,7 +571,7 @@ impl Unifier {
                 format!("virtual[{}]", self.stringify(*ty, obj_to_name, var_to_name))
             }
             TypeEnum::TObj { obj_id, params, .. } => {
-                let name = obj_to_name(*obj_id);
+                let name = obj_to_name(obj_id.0);
                 if !params.is_empty() {
                     let mut params =
                         params.values().map(|v| self.stringify(*v, obj_to_name, var_to_name));
diff --git a/nac3core/src/typecheck/typedef/test.rs b/nac3core/src/typecheck/typedef/test.rs
index f200dc18c..0e4a32f8b 100644
--- a/nac3core/src/typecheck/typedef/test.rs
+++ b/nac3core/src/typecheck/typedef/test.rs
@@ -78,7 +78,7 @@ impl TestEnvironment {
         type_mapping.insert(
             "int".into(),
             unifier.add_ty(TypeEnum::TObj {
-                obj_id: 0,
+                obj_id: DefinitionId(0),
                 fields: HashMap::new().into(),
                 params: HashMap::new(),
             }),
@@ -86,7 +86,7 @@ impl TestEnvironment {
         type_mapping.insert(
             "float".into(),
             unifier.add_ty(TypeEnum::TObj {
-                obj_id: 1,
+                obj_id: DefinitionId(1),
                 fields: HashMap::new().into(),
                 params: HashMap::new(),
             }),
@@ -94,7 +94,7 @@ impl TestEnvironment {
         type_mapping.insert(
             "bool".into(),
             unifier.add_ty(TypeEnum::TObj {
-                obj_id: 2,
+                obj_id: DefinitionId(2),
                 fields: HashMap::new().into(),
                 params: HashMap::new(),
             }),
@@ -103,7 +103,7 @@ impl TestEnvironment {
         type_mapping.insert(
             "Foo".into(),
             unifier.add_ty(TypeEnum::TObj {
-                obj_id: 3,
+                obj_id: DefinitionId(3),
                 fields: [("a".into(), v0)].iter().cloned().collect::<HashMap<_, _>>().into(),
                 params: [(id, v0)].iter().cloned().collect(),
             }),
@@ -334,7 +334,7 @@ fn test_virtual() {
         vars: HashMap::new(),
     }));
     let bar = env.unifier.add_ty(TypeEnum::TObj {
-        obj_id: 5,
+        obj_id: DefinitionId(5),
         fields: [("f".to_string(), fun), ("a".to_string(), int)]
             .iter()
             .cloned()