diff --git a/midas/ast/printer/midas.py b/midas/ast/printer/midas.py
index 56d7ce8..f064751 100644
--- a/midas/ast/printer/midas.py
+++ b/midas/ast/printer/midas.py
@@ -1,6 +1,9 @@
+from typing import final
+
 import midas.ast.midas as m
 
 
+@final
 class MidasPrinter(
     m.Expr.Visitor[str],
     m.Stmt.Visitor[str],
diff --git a/midas/ast/printer/midas_ast.py b/midas/ast/printer/midas_ast.py
index d2e5daf..2e8103b 100644
--- a/midas/ast/printer/midas_ast.py
+++ b/midas/ast/printer/midas_ast.py
@@ -1,7 +1,10 @@
+from typing import final
+
 import midas.ast.midas as m
 from midas.ast.printer.base import AstPrinter
 
 
+@final
 class MidasAstPrinter(
     AstPrinter,
     m.Expr.Visitor[None],
diff --git a/midas/ast/printer/python_ast.py b/midas/ast/printer/python_ast.py
index d2214e0..70a2223 100644
--- a/midas/ast/printer/python_ast.py
+++ b/midas/ast/printer/python_ast.py
@@ -1,9 +1,11 @@
 import ast
+from typing import final
 
 import midas.ast.python as p
 from midas.ast.printer.base import AstPrinter
 
 
+@final
 class PythonAstPrinter(
     AstPrinter,
     p.MidasType.Visitor[None],
diff --git a/midas/checker/evaluator.py b/midas/checker/evaluator.py
index 79dc9c1..a3b4f96 100644
--- a/midas/checker/evaluator.py
+++ b/midas/checker/evaluator.py
@@ -1,5 +1,5 @@
 from dataclasses import dataclass
-from typing import Any, Callable, Optional
+from typing import Any, Callable, Optional, final
 
 import midas.ast.midas as m
 from midas.ast.location import Location
@@ -18,6 +18,7 @@ class PartialPredicate(Predicate):
     """A dictionary of already applied parameters"""
 
 
+@final
 class Evaluator(m.Expr.Visitor[Any]):
     """Helper class to evaluate an expression
 
diff --git a/midas/checker/midas.py b/midas/checker/midas.py
index cd691ea..4ec4f73 100644
--- a/midas/checker/midas.py
+++ b/midas/checker/midas.py
@@ -1,6 +1,6 @@
 import logging
 from pathlib import Path
-from typing import Optional
+from typing import Optional, final
 
 import midas.ast.midas as m
 from midas.ast.location import Location
@@ -30,6 +30,7 @@ from midas.lexer.token import Token, TokenType
 from midas.parser.midas import MidasParser
 
 
+@final
 class MidasTyper(m.Stmt.Visitor[None], m.Expr.Visitor[Type], m.Type.Visitor[Type]):
     """A resolver which evaluates Midas type definitions and build a registry"""
 
diff --git a/midas/checker/python.py b/midas/checker/python.py
index 15f4b62..b2995d0 100644
--- a/midas/checker/python.py
+++ b/midas/checker/python.py
@@ -1,6 +1,6 @@
 import ast
 import logging
-from typing import Any, Optional
+from typing import Any, Optional, final
 
 import midas.ast.python as p
 from midas.ast.location import Location
@@ -55,6 +55,7 @@ class UndefinedMethodException(Exception):
     pass
 
 
+@final
 class PythonTyper(
     p.Stmt.Visitor[None],
     p.Expr.Visitor[Type],
diff --git a/midas/checker/resolver.py b/midas/checker/resolver.py
index 7c9e4e4..70747e9 100644
--- a/midas/checker/resolver.py
+++ b/midas/checker/resolver.py
@@ -1,3 +1,5 @@
+from typing import final
+
 import midas.ast.python as p
 from midas.ast.location import Location
 from midas.checker.reporter import FileReporter
@@ -6,6 +8,7 @@ from midas.checker.reporter import FileReporter
 class ResolverError(Exception): ...
 
 
+@final
 class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
     """A variable assignment and reference resolver
 
diff --git a/midas/cli/highlighter.py b/midas/cli/highlighter.py
index 4929b0c..6086463 100644
--- a/midas/cli/highlighter.py
+++ b/midas/cli/highlighter.py
@@ -3,7 +3,7 @@ from __future__ import annotations
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
 from pathlib import Path
-from typing import Generic, Optional, Protocol, TextIO, TypeVar
+from typing import Generic, Optional, Protocol, TextIO, TypeVar, final
 
 import midas.ast.midas as m
 import midas.ast.python as p
@@ -121,6 +121,7 @@ class Highlighter(ABC):
                 self.openings.setdefault((l + 1, 0), []).append(opening)
 
 
+@final
 class PythonHighlighter(
     Highlighter,
     p.MidasType.Visitor[None],
@@ -255,6 +256,7 @@ class PythonHighlighter(
     def visit_raw_stmt(self, stmt: p.RawStmt) -> None: ...
 
 
+@final
 class MidasHighlighter(
     Highlighter, m.Stmt.Visitor[None], m.Expr.Visitor[None], m.Type.Visitor[None]
 ):
@@ -352,6 +354,7 @@ class MidasHighlighter(
         self.wrap(column, "column")
 
 
+@final
 class DiagnosticsHighlighter(Highlighter):
     EXTRA_CSS_PATH: Optional[Path] = Path(__file__).parent / "hl_diagnostic.css"
 
diff --git a/midas/generator/constraints.py b/midas/generator/constraints.py
index 75c9a15..b663a9a 100644
--- a/midas/generator/constraints.py
+++ b/midas/generator/constraints.py
@@ -1,5 +1,5 @@
 import ast
-from typing import Optional
+from typing import Optional, final
 
 import midas.ast.midas as m
 from midas.checker.registry import TypesRegistry
@@ -39,6 +39,7 @@ COMPARISON_OPERATORS: dict[TokenType, type[ast.cmpop]] = {
 }
 
 
+@final
 class ConstraintGenerator(m.Expr.Visitor[ast.expr]):
     """Class to generate Python code for constraint expressions"""
 
diff --git a/midas/generator/generator.py b/midas/generator/generator.py
index 3cf2423..fe3b92e 100644
--- a/midas/generator/generator.py
+++ b/midas/generator/generator.py
@@ -3,7 +3,7 @@ import logging
 import shutil
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import Optional, assert_never
+from typing import Optional, assert_never, final
 
 import midas.ast.midas as m
 import midas.ast.python as p
@@ -47,6 +47,7 @@ class Scope:
     """A list of aliases defined in the scope, that can be discard afterwards"""
 
 
+@final
 class Generator(p.Stmt.Visitor[ast.stmt], p.Expr.Visitor[ast.expr]):
     """
     A class to translate the custom Python AST back into raw `ast` nodes
diff --git a/tests/serializer/midas.py b/tests/serializer/midas.py
index 599482b..38640f6 100644
--- a/tests/serializer/midas.py
+++ b/tests/serializer/midas.py
@@ -1,4 +1,4 @@
-from typing import Optional, Sequence
+from typing import Optional, Sequence, final
 
 from midas.ast.midas import (
     AliasStmt,
@@ -28,6 +28,7 @@ from midas.ast.midas import (
 )
 
 
+@final
 class MidasAstJsonSerializer(
     Stmt.Visitor[dict], Expr.Visitor[dict], Type.Visitor[dict]
 ):
diff --git a/tests/serializer/python.py b/tests/serializer/python.py
index 89a097c..dca4cb2 100644
--- a/tests/serializer/python.py
+++ b/tests/serializer/python.py
@@ -1,5 +1,5 @@
 import ast
-from typing import Optional, Sequence, Type
+from typing import Optional, Sequence, Type, final
 
 from midas.ast.python import (
     AssignStmt,
@@ -78,6 +78,7 @@ boolean_ops: dict[Type[ast.boolop], str] = {
 }
 
 
+@final
 class PythonAstJsonSerializer(
     Stmt.Visitor[dict], Expr.Visitor[dict], MidasType.Visitor[dict]
 ):