diff --git a/Lib/test/test_funcattrs.py b/Lib/test/test_funcattrs.py
index 5fd268fd902..3d5378092b4 100644
--- a/Lib/test/test_funcattrs.py
+++ b/Lib/test/test_funcattrs.py
@@ -176,8 +176,6 @@ def test___name__(self):
         self.assertEqual(self.fi.a.__name__, 'a')
         self.cannot_set_attr(self.fi.a, "__name__", 'a', AttributeError)
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test___qualname__(self):
         # PEP 3155
         self.assertEqual(self.b.__qualname__, 'FuncAttrsTest.setUp.<locals>.b')
diff --git a/Lib/test/test_reprlib.py b/Lib/test/test_reprlib.py
index 396be4b1044..738b48f5623 100644
--- a/Lib/test/test_reprlib.py
+++ b/Lib/test/test_reprlib.py
@@ -176,8 +176,6 @@ def test_instance(self):
         self.assertTrue(s.endswith(">"))
         self.assertIn(s.find("..."), [12, 13])
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_lambda(self):
         r = repr(lambda x: x)
         self.assertTrue(r.startswith("<function ReprTests.test_lambda.<locals>.<lambda"), r)
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index 96fddfce030..229d61ad15f 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -5353,8 +5353,6 @@ class A:
             some.__no_type_check__
         self.assertEqual(get_type_hints(some), {'args': int, 'return': int})
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_no_type_check_lambda(self):
         @no_type_check
         class A:
diff --git a/compiler/codegen/src/compile.rs b/compiler/codegen/src/compile.rs
index 96f6f9a3c53..6e8ab9554a0 100644
--- a/compiler/codegen/src/compile.rs
+++ b/compiler/codegen/src/compile.rs
@@ -1482,26 +1482,7 @@ impl Compiler<'_> {
         Ok(())
     }
 
-    fn enter_function(
-        &mut self,
-        name: &str,
-        parameters: &Parameters,
-    ) -> CompileResult<bytecode::MakeFunctionFlags> {
-        let defaults: Vec<_> = std::iter::empty()
-            .chain(&parameters.posonlyargs)
-            .chain(&parameters.args)
-            .filter_map(|x| x.default.as_deref())
-            .collect();
-        let have_defaults = !defaults.is_empty();
-        if have_defaults {
-            // Construct a tuple:
-            let size = defaults.len().to_u32();
-            for element in &defaults {
-                self.compile_expression(element)?;
-            }
-            emit!(self, Instruction::BuildTuple { size });
-        }
-
+    fn enter_function(&mut self, name: &str, parameters: &Parameters) -> CompileResult<()> {
         // TODO: partition_in_place
         let mut kw_without_defaults = vec![];
         let mut kw_with_defaults = vec![];
@@ -1513,31 +1494,6 @@ impl Compiler<'_> {
             }
         }
 
-        // let (kw_without_defaults, kw_with_defaults) = args.split_kwonlyargs();
-        if !kw_with_defaults.is_empty() {
-            let default_kw_count = kw_with_defaults.len();
-            for (arg, default) in kw_with_defaults.iter() {
-                self.emit_load_const(ConstantData::Str {
-                    value: arg.name.as_str().into(),
-                });
-                self.compile_expression(default)?;
-            }
-            emit!(
-                self,
-                Instruction::BuildMap {
-                    size: default_kw_count.to_u32(),
-                }
-            );
-        }
-
-        let mut func_flags = bytecode::MakeFunctionFlags::empty();
-        if have_defaults {
-            func_flags |= bytecode::MakeFunctionFlags::DEFAULTS;
-        }
-        if !kw_with_defaults.is_empty() {
-            func_flags |= bytecode::MakeFunctionFlags::KW_ONLY_DEFAULTS;
-        }
-
         self.push_output(
             bytecode::CodeFlags::NEW_LOCALS | bytecode::CodeFlags::IS_OPTIMIZED,
             parameters.posonlyargs.len().to_u32(),
@@ -1565,7 +1521,7 @@ impl Compiler<'_> {
             self.varname(name.name.as_str())?;
         }
 
-        Ok(func_flags)
+        Ok(())
     }
 
     fn prepare_decorators(&mut self, decorator_list: &[Decorator]) -> CompileResult<()> {
@@ -1869,7 +1825,57 @@ impl Compiler<'_> {
             self.push_symbol_table();
         }
 
-        let mut func_flags = self.enter_function(name, parameters)?;
+        // Prepare defaults and kwdefaults before entering function
+        let defaults: Vec<_> = std::iter::empty()
+            .chain(&parameters.posonlyargs)
+            .chain(&parameters.args)
+            .filter_map(|x| x.default.as_deref())
+            .collect();
+        let have_defaults = !defaults.is_empty();
+
+        // Compile defaults before entering function scope
+        if have_defaults {
+            // Construct a tuple:
+            let size = defaults.len().to_u32();
+            for element in &defaults {
+                self.compile_expression(element)?;
+            }
+            emit!(self, Instruction::BuildTuple { size });
+        }
+
+        // Prepare keyword-only defaults
+        let mut kw_with_defaults = vec![];
+        for kwonlyarg in &parameters.kwonlyargs {
+            if let Some(default) = &kwonlyarg.default {
+                kw_with_defaults.push((&kwonlyarg.parameter, default));
+            }
+        }
+
+        let have_kwdefaults = !kw_with_defaults.is_empty();
+        if have_kwdefaults {
+            let default_kw_count = kw_with_defaults.len();
+            for (arg, default) in kw_with_defaults.iter() {
+                self.emit_load_const(ConstantData::Str {
+                    value: arg.name.as_str().into(),
+                });
+                self.compile_expression(default)?;
+            }
+            emit!(
+                self,
+                Instruction::BuildMap {
+                    size: default_kw_count.to_u32(),
+                }
+            );
+        }
+
+        self.enter_function(name, parameters)?;
+        let mut func_flags = bytecode::MakeFunctionFlags::empty();
+        if have_defaults {
+            func_flags |= bytecode::MakeFunctionFlags::DEFAULTS;
+        }
+        if have_kwdefaults {
+            func_flags |= bytecode::MakeFunctionFlags::KW_ONLY_DEFAULTS;
+        }
         self.current_code_info()
             .flags
             .set(bytecode::CodeFlags::IS_COROUTINE, is_async);
@@ -1888,7 +1894,7 @@ impl Compiler<'_> {
         };
 
         // Set qualname using the new method
-        let qualname = self.set_qualname();
+        self.set_qualname();
 
         let (doc_str, body) = split_doc(body, &self.opts);
 
@@ -1965,7 +1971,7 @@ impl Compiler<'_> {
         }
 
         // Create function with closure
-        self.make_closure(code, &qualname, func_flags)?;
+        self.make_closure(code, func_flags)?;
 
         if let Some(value) = doc_str {
             emit!(self, Instruction::Duplicate);
@@ -1982,58 +1988,92 @@ impl Compiler<'_> {
         self.store_name(name)
     }
 
+    /// Determines if a variable should be CELL or FREE type
+    // = get_ref_type
+    fn get_ref_type(&self, name: &str) -> Result<SymbolScope, CodegenErrorType> {
+        // Special handling for __class__ and __classdict__ in class scope
+        if self.ctx.in_class && (name == "__class__" || name == "__classdict__") {
+            return Ok(SymbolScope::Cell);
+        }
+
+        let table = self.symbol_table_stack.last().unwrap();
+        match table.lookup(name) {
+            Some(symbol) => match symbol.scope {
+                SymbolScope::Cell | SymbolScope::TypeParams => Ok(SymbolScope::Cell),
+                SymbolScope::Free => Ok(SymbolScope::Free),
+                _ if symbol.flags.contains(SymbolFlags::FREE_CLASS) => Ok(SymbolScope::Free),
+                _ => Err(CodegenErrorType::SyntaxError(format!(
+                    "get_ref_type: invalid scope for '{name}'"
+                ))),
+            },
+            None => Err(CodegenErrorType::SyntaxError(format!(
+                "get_ref_type: cannot find symbol '{name}'"
+            ))),
+        }
+    }
+
     /// Loads closure variables if needed and creates a function object
     // = compiler_make_closure
     fn make_closure(
         &mut self,
         code: CodeObject,
-        qualname: &str,
-        mut flags: bytecode::MakeFunctionFlags,
+        flags: bytecode::MakeFunctionFlags,
     ) -> CompileResult<()> {
         // Handle free variables (closure)
-        if !code.freevars.is_empty() {
+        let has_freevars = !code.freevars.is_empty();
+        if has_freevars {
             // Build closure tuple by loading free variables
+
             for var in &code.freevars {
-                let table = self.symbol_table_stack.last().unwrap();
-                let symbol = match table.lookup(var) {
-                    Some(s) => s,
-                    None => {
-                        return Err(self.error(CodegenErrorType::SyntaxError(format!(
-                            "compiler_make_closure: cannot find symbol '{var}'",
-                        ))));
-                    }
-                };
+                // Special case: If a class contains a method with a
+                // free variable that has the same name as a method,
+                // the name will be considered free *and* local in the
+                // class. It should be handled by the closure, as
+                // well as by the normal name lookup logic.
+
+                // Get reference type using our get_ref_type function
+                let ref_type = self.get_ref_type(var).map_err(|e| self.error(e))?;
 
+                // Get parent code info
                 let parent_code = self.code_stack.last().unwrap();
-                let vars = match symbol.scope {
-                    SymbolScope::Free => &parent_code.metadata.freevars,
-                    SymbolScope::Cell => &parent_code.metadata.cellvars,
-                    SymbolScope::TypeParams => &parent_code.metadata.cellvars,
-                    _ if symbol.flags.contains(SymbolFlags::FREE_CLASS) => {
-                        &parent_code.metadata.freevars
-                    }
+                let cellvars_len = parent_code.metadata.cellvars.len();
+
+                // Look up the variable index based on reference type
+                let idx = match ref_type {
+                    SymbolScope::Cell => parent_code
+                        .metadata
+                        .cellvars
+                        .get_index_of(var)
+                        .or_else(|| {
+                            parent_code
+                                .metadata
+                                .freevars
+                                .get_index_of(var)
+                                .map(|i| i + cellvars_len)
+                        })
+                        .ok_or_else(|| {
+                            self.error(CodegenErrorType::SyntaxError(format!(
+                                "compiler_make_closure: cannot find '{var}' in parent vars",
+                            )))
+                        })?,
+                    SymbolScope::Free => parent_code
+                        .metadata
+                        .freevars
+                        .get_index_of(var)
+                        .map(|i| i + cellvars_len)
+                        .or_else(|| parent_code.metadata.cellvars.get_index_of(var))
+                        .ok_or_else(|| {
+                            self.error(CodegenErrorType::SyntaxError(format!(
+                                "compiler_make_closure: cannot find '{var}' in parent vars",
+                            )))
+                        })?,
                     _ => {
                         return Err(self.error(CodegenErrorType::SyntaxError(format!(
-                            "compiler_make_closure: invalid scope for '{var}'",
+                            "compiler_make_closure: unexpected ref_type {ref_type:?} for '{var}'",
                         ))));
                     }
                 };
 
-                let idx = match vars.get_index_of(var) {
-                    Some(i) => i,
-                    None => {
-                        return Err(self.error(CodegenErrorType::SyntaxError(format!(
-                            "compiler_make_closure: cannot find '{var}' in parent vars",
-                        ))));
-                    }
-                };
-
-                let idx = if let SymbolScope::Free = symbol.scope {
-                    idx + parent_code.metadata.cellvars.len()
-                } else {
-                    idx
-                };
-
                 emit!(self, Instruction::LoadClosure(idx.to_u32()));
             }
 
@@ -2044,22 +2084,73 @@ impl Compiler<'_> {
                     size: code.freevars.len().to_u32(),
                 }
             );
-
-            flags |= bytecode::MakeFunctionFlags::CLOSURE;
         }
 
-        // Load code object
+        // load code object and create function
         self.emit_load_const(ConstantData::Code {
             code: Box::new(code),
         });
 
-        // Load qualified name
-        self.emit_load_const(ConstantData::Str {
-            value: qualname.into(),
-        });
+        // Create function with no flags
+        emit!(self, Instruction::MakeFunction);
+
+        // Now set attributes one by one using SET_FUNCTION_ATTRIBUTE
+        // Note: The order matters! Values must be on stack before calling SET_FUNCTION_ATTRIBUTE
+
+        // Set closure if needed
+        if has_freevars {
+            // Closure tuple is already on stack
+            emit!(
+                self,
+                Instruction::SetFunctionAttribute {
+                    attr: bytecode::MakeFunctionFlags::CLOSURE
+                }
+            );
+        }
+
+        // Set annotations if present
+        if flags.contains(bytecode::MakeFunctionFlags::ANNOTATIONS) {
+            // Annotations dict is already on stack
+            emit!(
+                self,
+                Instruction::SetFunctionAttribute {
+                    attr: bytecode::MakeFunctionFlags::ANNOTATIONS
+                }
+            );
+        }
 
-        // Make function with proper flags
-        emit!(self, Instruction::MakeFunction(flags));
+        // Set kwdefaults if present
+        if flags.contains(bytecode::MakeFunctionFlags::KW_ONLY_DEFAULTS) {
+            // kwdefaults dict is already on stack
+            emit!(
+                self,
+                Instruction::SetFunctionAttribute {
+                    attr: bytecode::MakeFunctionFlags::KW_ONLY_DEFAULTS
+                }
+            );
+        }
+
+        // Set defaults if present
+        if flags.contains(bytecode::MakeFunctionFlags::DEFAULTS) {
+            // defaults tuple is already on stack
+            emit!(
+                self,
+                Instruction::SetFunctionAttribute {
+                    attr: bytecode::MakeFunctionFlags::DEFAULTS
+                }
+            );
+        }
+
+        // Set type_params if present
+        if flags.contains(bytecode::MakeFunctionFlags::TYPE_PARAMS) {
+            // type_params tuple is already on stack
+            emit!(
+                self,
+                Instruction::SetFunctionAttribute {
+                    attr: bytecode::MakeFunctionFlags::TYPE_PARAMS
+                }
+            );
+        }
 
         Ok(())
     }
@@ -2262,7 +2353,7 @@ impl Compiler<'_> {
             func_flags |= bytecode::MakeFunctionFlags::TYPE_PARAMS;
 
             // Create class function with closure
-            self.make_closure(class_code, name, func_flags)?;
+            self.make_closure(class_code, func_flags)?;
             self.emit_load_const(ConstantData::Str { value: name.into() });
 
             // Compile original bases
@@ -2311,19 +2402,14 @@ impl Compiler<'_> {
             let type_params_code = self.exit_scope();
 
             // Execute the type params function
-            let type_params_name = format!("<generic parameters of {name}>");
-            self.make_closure(
-                type_params_code,
-                &type_params_name,
-                bytecode::MakeFunctionFlags::empty(),
-            )?;
+            self.make_closure(type_params_code, bytecode::MakeFunctionFlags::empty())?;
             emit!(self, Instruction::CallFunctionPositional { nargs: 0 });
         } else {
             // Non-generic class: standard path
             emit!(self, Instruction::LoadBuildClass);
 
             // Create class function with closure
-            self.make_closure(class_code, name, bytecode::MakeFunctionFlags::empty())?;
+            self.make_closure(class_code, bytecode::MakeFunctionFlags::empty())?;
             self.emit_load_const(ConstantData::Str { value: name.into() });
 
             let call = if let Some(arguments) = arguments {
@@ -4033,10 +4119,59 @@ impl Compiler<'_> {
                 parameters, body, ..
             }) => {
                 let prev_ctx = self.ctx;
-
                 let name = "<lambda>".to_owned();
-                let func_flags = self
-                    .enter_function(&name, parameters.as_deref().unwrap_or(&Default::default()))?;
+                let default_params = Default::default();
+                let params = parameters.as_deref().unwrap_or(&default_params);
+
+                // Prepare defaults before entering function
+                let defaults: Vec<_> = std::iter::empty()
+                    .chain(&params.posonlyargs)
+                    .chain(&params.args)
+                    .filter_map(|x| x.default.as_deref())
+                    .collect();
+                let have_defaults = !defaults.is_empty();
+
+                if have_defaults {
+                    let size = defaults.len().to_u32();
+                    for element in &defaults {
+                        self.compile_expression(element)?;
+                    }
+                    emit!(self, Instruction::BuildTuple { size });
+                }
+
+                // Prepare keyword-only defaults
+                let mut kw_with_defaults = vec![];
+                for kwonlyarg in &params.kwonlyargs {
+                    if let Some(default) = &kwonlyarg.default {
+                        kw_with_defaults.push((&kwonlyarg.parameter, default));
+                    }
+                }
+
+                let have_kwdefaults = !kw_with_defaults.is_empty();
+                if have_kwdefaults {
+                    let default_kw_count = kw_with_defaults.len();
+                    for (arg, default) in kw_with_defaults.iter() {
+                        self.emit_load_const(ConstantData::Str {
+                            value: arg.name.as_str().into(),
+                        });
+                        self.compile_expression(default)?;
+                    }
+                    emit!(
+                        self,
+                        Instruction::BuildMap {
+                            size: default_kw_count.to_u32(),
+                        }
+                    );
+                }
+
+                self.enter_function(&name, params)?;
+                let mut func_flags = bytecode::MakeFunctionFlags::empty();
+                if have_defaults {
+                    func_flags |= bytecode::MakeFunctionFlags::DEFAULTS;
+                }
+                if have_kwdefaults {
+                    func_flags |= bytecode::MakeFunctionFlags::KW_ONLY_DEFAULTS;
+                }
 
                 // Set qualname for lambda
                 self.set_qualname();
@@ -4057,7 +4192,7 @@ impl Compiler<'_> {
                 let code = self.exit_scope();
 
                 // Create lambda function with closure
-                self.make_closure(code, &name, func_flags)?;
+                self.make_closure(code, func_flags)?;
 
                 self.ctx = prev_ctx;
             }
@@ -4602,7 +4737,7 @@ impl Compiler<'_> {
         self.ctx = prev_ctx;
 
         // Create comprehension function with closure
-        self.make_closure(code, name, bytecode::MakeFunctionFlags::empty())?;
+        self.make_closure(code, bytecode::MakeFunctionFlags::empty())?;
 
         // Evaluate iterated item:
         self.compile_expression(&generators[0].iter)?;
diff --git a/compiler/codegen/src/symboltable.rs b/compiler/codegen/src/symboltable.rs
index 16a65bca116..7f7355bd734 100644
--- a/compiler/codegen/src/symboltable.rs
+++ b/compiler/codegen/src/symboltable.rs
@@ -127,6 +127,7 @@ pub enum SymbolScope {
     GlobalImplicit,
     Free,
     Cell,
+    // TODO: wrong place. not a symbol scope, but a COMPILER_SCOPE_TYPEPARAMS
     TypeParams,
 }
 
diff --git a/compiler/core/src/bytecode.rs b/compiler/core/src/bytecode.rs
index 3e74fe62738..0a6f3bf20d6 100644
--- a/compiler/core/src/bytecode.rs
+++ b/compiler/core/src/bytecode.rs
@@ -528,7 +528,10 @@ pub enum Instruction {
     JumpIfFalseOrPop {
         target: Arg<Label>,
     },
-    MakeFunction(Arg<MakeFunctionFlags>),
+    MakeFunction,
+    SetFunctionAttribute {
+        attr: Arg<MakeFunctionFlags>,
+    },
     CallFunctionPositional {
         nargs: Arg<u32>,
     },
@@ -1296,13 +1299,13 @@ impl Instruction {
                     -1
                 }
             }
-            MakeFunction(flags) => {
-                let flags = flags.get(arg);
-                -2 - flags.contains(MakeFunctionFlags::CLOSURE) as i32
-                    - flags.contains(MakeFunctionFlags::ANNOTATIONS) as i32
-                    - flags.contains(MakeFunctionFlags::KW_ONLY_DEFAULTS) as i32
-                    - flags.contains(MakeFunctionFlags::DEFAULTS) as i32
-                    + 1
+            MakeFunction => {
+                // CPython 3.13 style: MakeFunction only pops code object
+                -1 + 1 // pop code, push function
+            }
+            SetFunctionAttribute { .. } => {
+                // pops attribute value and function, pushes function back
+                -2 + 1
             }
             CallFunctionPositional { nargs } => -(nargs.get(arg) as i32) - 1 + 1,
             CallMethodPositional { nargs } => -(nargs.get(arg) as i32) - 3 + 1,
@@ -1497,7 +1500,8 @@ impl Instruction {
             JumpIfFalse { target } => w!(JumpIfFalse, target),
             JumpIfTrueOrPop { target } => w!(JumpIfTrueOrPop, target),
             JumpIfFalseOrPop { target } => w!(JumpIfFalseOrPop, target),
-            MakeFunction(flags) => w!(MakeFunction, ?flags),
+            MakeFunction => w!(MakeFunction),
+            SetFunctionAttribute { attr } => w!(SetFunctionAttribute, ?attr),
             CallFunctionPositional { nargs } => w!(CallFunctionPositional, nargs),
             CallFunctionKeyword { nargs } => w!(CallFunctionKeyword, nargs),
             CallFunctionEx { has_kwargs } => w!(CallFunctionEx, has_kwargs),
diff --git a/jit/tests/common.rs b/jit/tests/common.rs
index 16a4fded46e..a88d3207f2a 100644
--- a/jit/tests/common.rs
+++ b/jit/tests/common.rs
@@ -122,24 +122,47 @@ impl StackMachine {
                 }
                 self.stack.push(StackValue::Map(map));
             }
-            Instruction::MakeFunction(_flags) => {
-                let _name = if let Some(StackValue::String(name)) = self.stack.pop() {
-                    name
-                } else {
-                    panic!("Expected function name")
-                };
+            Instruction::MakeFunction => {
                 let code = if let Some(StackValue::Code(code)) = self.stack.pop() {
                     code
                 } else {
                     panic!("Expected function code")
                 };
-                let annotations = if let Some(StackValue::Map(map)) = self.stack.pop() {
-                    map
+                // Other attributes will be set by SET_FUNCTION_ATTRIBUTE
+                self.stack.push(StackValue::Function(Function {
+                    code,
+                    annotations: HashMap::new(), // empty annotations, will be set later if needed
+                }));
+            }
+            Instruction::SetFunctionAttribute { attr } => {
+                // Stack: [..., attr_value, func] -> [..., func]
+                let func = if let Some(StackValue::Function(func)) = self.stack.pop() {
+                    func
                 } else {
-                    panic!("Expected function annotations")
+                    panic!("Expected function on stack for SET_FUNCTION_ATTRIBUTE")
                 };
-                self.stack
-                    .push(StackValue::Function(Function { code, annotations }));
+                let attr_value = self.stack.pop().expect("Expected attribute value on stack");
+
+                // For now, we only handle ANNOTATIONS flag in JIT tests
+                if attr
+                    .get(arg)
+                    .contains(rustpython_compiler_core::bytecode::MakeFunctionFlags::ANNOTATIONS)
+                {
+                    if let StackValue::Map(annotations) = attr_value {
+                        // Update function's annotations
+                        let updated_func = Function {
+                            code: func.code,
+                            annotations,
+                        };
+                        self.stack.push(StackValue::Function(updated_func));
+                    } else {
+                        panic!("Expected annotations to be a map");
+                    }
+                } else {
+                    // For other attributes, just push the function back unchanged
+                    // (since JIT tests mainly care about type annotations)
+                    self.stack.push(StackValue::Function(func));
+                }
             }
             Instruction::Duplicate => {
                 let value = self.stack.last().unwrap().clone();
diff --git a/vm/src/builtins/function.rs b/vm/src/builtins/function.rs
index 16cb3e420f3..06a91ff36c5 100644
--- a/vm/src/builtins/function.rs
+++ b/vm/src/builtins/function.rs
@@ -36,11 +36,11 @@ pub struct PyFunction {
     name: PyMutex<PyStrRef>,
     qualname: PyMutex<PyStrRef>,
     type_params: PyMutex<PyTupleRef>,
-    #[cfg(feature = "jit")]
-    jitted_code: OnceCell<CompiledCode>,
     annotations: PyMutex<PyDictRef>,
     module: PyMutex<PyObjectRef>,
     doc: PyMutex<PyObjectRef>,
+    #[cfg(feature = "jit")]
+    jitted_code: OnceCell<CompiledCode>,
 }
 
 unsafe impl Traverse for PyFunction {
@@ -54,18 +54,10 @@ unsafe impl Traverse for PyFunction {
 }
 
 impl PyFunction {
-    #[allow(clippy::too_many_arguments)]
     #[inline]
     pub(crate) fn new(
         code: PyRef<PyCode>,
         globals: PyDictRef,
-        closure: Option<PyRef<PyTuple<PyCellRef>>>,
-        defaults: Option<PyTupleRef>,
-        kw_only_defaults: Option<PyDictRef>,
-        qualname: PyStrRef,
-        type_params: PyTupleRef,
-        annotations: PyDictRef,
-        doc: PyObjectRef,
         vm: &VirtualMachine,
     ) -> PyResult<Self> {
         let name = PyMutex::new(code.obj_name.to_owned());
@@ -79,27 +71,22 @@ impl PyFunction {
             }
         });
 
+        let qualname = vm.ctx.new_str(code.qualname.as_str());
         let func = Self {
-            code,
+            code: code.clone(),
             globals,
             builtins,
-            closure,
-            defaults_and_kwdefaults: PyMutex::new((defaults, kw_only_defaults)),
+            closure: None,
+            defaults_and_kwdefaults: PyMutex::new((None, None)),
             name,
             qualname: PyMutex::new(qualname),
-            type_params: PyMutex::new(type_params),
-            annotations: PyMutex::new(annotations),
+            type_params: PyMutex::new(vm.ctx.empty_tuple.clone()),
+            annotations: PyMutex::new(vm.ctx.new_dict()),
             module: PyMutex::new(module),
-            doc: PyMutex::new(doc),
+            doc: PyMutex::new(vm.ctx.none()),
             #[cfg(feature = "jit")]
             jitted_code: OnceCell::new(),
         };
-
-        // let name = qualname.as_str().split('.').next_back().unwrap();
-        // func.set_attr(identifier!(vm, __name__), vm.new_pyobj(name), vm)?;
-        // func.set_attr(identifier!(vm, __qualname__), qualname, vm)?;
-        // func.set_attr(identifier!(vm, __doc__), doc, vm)?;
-
         Ok(func)
     }
 
@@ -316,6 +303,76 @@ impl PyFunction {
 
         Ok(())
     }
+
+    /// Set function attribute based on MakeFunctionFlags
+    pub(crate) fn set_function_attribute(
+        &mut self,
+        attr: bytecode::MakeFunctionFlags,
+        attr_value: PyObjectRef,
+        vm: &VirtualMachine,
+    ) -> PyResult<()> {
+        use crate::builtins::PyDict;
+        if attr == bytecode::MakeFunctionFlags::DEFAULTS {
+            let defaults = match attr_value.downcast::<PyTuple>() {
+                Ok(tuple) => tuple,
+                Err(obj) => {
+                    return Err(vm.new_type_error(format!(
+                        "__defaults__ must be a tuple, not {}",
+                        obj.class().name()
+                    )));
+                }
+            };
+            self.defaults_and_kwdefaults.lock().0 = Some(defaults);
+        } else if attr == bytecode::MakeFunctionFlags::KW_ONLY_DEFAULTS {
+            let kwdefaults = match attr_value.downcast::<PyDict>() {
+                Ok(dict) => dict,
+                Err(obj) => {
+                    return Err(vm.new_type_error(format!(
+                        "__kwdefaults__ must be a dict, not {}",
+                        obj.class().name()
+                    )));
+                }
+            };
+            self.defaults_and_kwdefaults.lock().1 = Some(kwdefaults);
+        } else if attr == bytecode::MakeFunctionFlags::ANNOTATIONS {
+            let annotations = match attr_value.downcast::<PyDict>() {
+                Ok(dict) => dict,
+                Err(obj) => {
+                    return Err(vm.new_type_error(format!(
+                        "__annotations__ must be a dict, not {}",
+                        obj.class().name()
+                    )));
+                }
+            };
+            *self.annotations.lock() = annotations;
+        } else if attr == bytecode::MakeFunctionFlags::CLOSURE {
+            // For closure, we need special handling
+            // The closure tuple contains cell objects
+            let closure_tuple = attr_value
+                .clone()
+                .downcast_exact::<PyTuple>(vm)
+                .map_err(|obj| {
+                    vm.new_type_error(format!(
+                        "closure must be a tuple, not {}",
+                        obj.class().name()
+                    ))
+                })?
+                .into_pyref();
+
+            self.closure = Some(closure_tuple.try_into_typed::<PyCell>(vm)?);
+        } else if attr == bytecode::MakeFunctionFlags::TYPE_PARAMS {
+            let type_params = attr_value.clone().downcast::<PyTuple>().map_err(|_| {
+                vm.new_type_error(format!(
+                    "__type_params__ must be a tuple, not {}",
+                    attr_value.class().name()
+                ))
+            })?;
+            *self.type_params.lock() = type_params;
+        } else {
+            unreachable!("This is a compiler bug");
+        }
+        Ok(())
+    }
 }
 
 impl Py<PyFunction> {
@@ -622,34 +679,23 @@ impl Constructor for PyFunction {
             None
         };
 
-        // Get function name - use provided name or default to code object name
-        let name = args
-            .name
-            .into_option()
-            .unwrap_or_else(|| PyStr::from(args.code.obj_name.as_str()).into_ref(&vm.ctx));
-
-        // Get qualname - for now just use the name
-        let qualname = name.clone();
-
-        // Create empty type_params and annotations
-        let type_params = vm.ctx.new_tuple(vec![]);
-        let annotations = vm.ctx.new_dict();
-
-        // Get doc from code object - for now just use None
-        let doc = vm.ctx.none();
-
-        let func = Self::new(
-            args.code,
-            args.globals,
-            closure,
-            args.defaults.into_option(),
-            args.kwdefaults.into_option(),
-            qualname,
-            type_params,
-            annotations,
-            doc,
-            vm,
-        )?;
+        let mut func = Self::new(args.code.clone(), args.globals.clone(), vm)?;
+        // Set function name if provided
+        if let Some(name) = args.name.into_option() {
+            *func.name.lock() = name.clone();
+            // Also update qualname to match the name
+            *func.qualname.lock() = name;
+        }
+        // Now set additional attributes directly
+        if let Some(closure_tuple) = closure {
+            func.closure = Some(closure_tuple);
+        }
+        if let Some(defaults) = args.defaults.into_option() {
+            func.defaults_and_kwdefaults.lock().0 = Some(defaults);
+        }
+        if let Some(kwdefaults) = args.kwdefaults.into_option() {
+            func.defaults_and_kwdefaults.lock().1 = Some(kwdefaults);
+        }
 
         func.into_ref_with_type(vm, cls).map(Into::into)
     }
diff --git a/vm/src/frame.rs b/vm/src/frame.rs
index 460ba4392ef..37fedfc4a5e 100644
--- a/vm/src/frame.rs
+++ b/vm/src/frame.rs
@@ -1159,8 +1159,9 @@ impl ExecutingFrame<'_> {
                 }
             }
             bytecode::Instruction::ForIter { target } => self.execute_for_iter(vm, target.get(arg)),
-            bytecode::Instruction::MakeFunction(flags) => {
-                self.execute_make_function(vm, flags.get(arg))
+            bytecode::Instruction::MakeFunction => self.execute_make_function(vm),
+            bytecode::Instruction::SetFunctionAttribute { attr } => {
+                self.execute_set_function_attribute(vm, attr.get(arg))
             }
             bytecode::Instruction::CallFunctionPositional { nargs } => {
                 let args = self.collect_positional_args(nargs.get(arg));
@@ -1827,79 +1828,46 @@ impl ExecutingFrame<'_> {
             }
         }
     }
-    fn execute_make_function(
-        &mut self,
-        vm: &VirtualMachine,
-        flags: bytecode::MakeFunctionFlags,
-    ) -> FrameResult {
-        let qualified_name = self
-            .pop_value()
-            .downcast::<PyStr>()
-            .expect("qualified name to be a string");
+    fn execute_make_function(&mut self, vm: &VirtualMachine) -> FrameResult {
+        // MakeFunction only takes code object, no flags
         let code_obj: PyRef<PyCode> = self
             .pop_value()
             .downcast()
-            .expect("Second to top value on the stack must be a code object");
-
-        let closure = if flags.contains(bytecode::MakeFunctionFlags::CLOSURE) {
-            let tuple = PyTupleRef::try_from_object(vm, self.pop_value()).unwrap();
-            Some(tuple.try_into_typed(vm).expect("This is a compiler bug"))
-        } else {
-            None
-        };
+            .expect("Stack value should be code object");
 
-        let annotations = if flags.contains(bytecode::MakeFunctionFlags::ANNOTATIONS) {
-            self.pop_value()
-        } else {
-            vm.ctx.new_dict().into()
-        };
+        // Create function with minimal attributes
+        let func_obj = PyFunction::new(code_obj, self.globals.clone(), vm)?.into_pyobject(vm);
 
-        let type_params: PyTupleRef = if flags.contains(bytecode::MakeFunctionFlags::TYPE_PARAMS) {
-            self.pop_value()
-                .downcast()
-                .map_err(|_| vm.new_type_error("Type params must be a tuple."))?
-        } else {
-            vm.ctx.empty_tuple.clone()
-        };
+        self.push_value(func_obj);
+        Ok(None)
+    }
 
-        let kw_only_defaults = if flags.contains(bytecode::MakeFunctionFlags::KW_ONLY_DEFAULTS) {
-            Some(
-                self.pop_value()
-                    .downcast::<PyDict>()
-                    .expect("Stack value for keyword only defaults expected to be a dict"),
-            )
-        } else {
-            None
-        };
+    fn execute_set_function_attribute(
+        &mut self,
+        vm: &VirtualMachine,
+        attr: bytecode::MakeFunctionFlags,
+    ) -> FrameResult {
+        // CPython 3.13 style: SET_FUNCTION_ATTRIBUTE sets attributes on a function
+        // Stack: [..., attr_value, func] -> [..., func]
+        // Stack order: func is at -1, attr_value is at -2
 
-        let defaults = if flags.contains(bytecode::MakeFunctionFlags::DEFAULTS) {
-            Some(
-                self.pop_value()
-                    .downcast::<PyTuple>()
-                    .expect("Stack value for defaults expected to be a tuple"),
-            )
-        } else {
-            None
+        let func = self.pop_value();
+        let attr_value = self.replace_top(func);
+
+        let func = self.top_value();
+        // Get the function reference and call the new method
+        let func_ref = func
+            .downcast_ref::<PyFunction>()
+            .expect("SET_FUNCTION_ATTRIBUTE expects function on stack");
+
+        let payload: &PyFunction = func_ref.payload();
+        // SetFunctionAttribute always follows MakeFunction, so at this point
+        // there are no other references to func. It is therefore safe to treat it as mutable.
+        unsafe {
+            let payload_ptr = payload as *const PyFunction as *mut PyFunction;
+            (*payload_ptr).set_function_attribute(attr, attr_value, vm)?;
         };
 
-        // pop argc arguments
-        // argument: name, args, globals
-        // let scope = self.scope.clone();
-        let func_obj = PyFunction::new(
-            code_obj,
-            self.globals.clone(),
-            closure,
-            defaults,
-            kw_only_defaults,
-            qualified_name.clone(),
-            type_params,
-            annotations.downcast().unwrap(),
-            vm.ctx.none(),
-            vm,
-        )?
-        .into_pyobject(vm);
-
-        self.push_value(func_obj);
         Ok(None)
     }
 
diff --git a/vm/src/object/core.rs b/vm/src/object/core.rs
index 5012855133a..f0f438e3aa6 100644
--- a/vm/src/object/core.rs
+++ b/vm/src/object/core.rs
@@ -906,6 +906,11 @@ impl<T: PyObjectPayload> Py<T> {
             _marker: PhantomData,
         })
     }
+
+    pub fn payload(&self) -> &T {
+        // SAFETY: we know the payload is T because of the type parameter
+        unsafe { self.as_object().payload_unchecked() }
+    }
 }
 
 impl<T> ToOwned for Py<T> {
@@ -1018,11 +1023,23 @@ impl<T> Clone for PyRef<T> {
 }
 
 impl<T: PyObjectPayload> PyRef<T> {
+    // #[inline(always)]
+    // pub(crate) const fn into_non_null(self) -> NonNull<Py<T>> {
+    //     let ptr = self.ptr;
+    //     std::mem::forget(self);
+    //     ptr
+    // }
+
+    #[inline(always)]
+    pub(crate) const unsafe fn from_non_null(ptr: NonNull<Py<T>>) -> Self {
+        Self { ptr }
+    }
+
+    /// # Safety
+    /// The raw pointer must point to a valid `Py<T>` object
     #[inline(always)]
     pub(crate) const unsafe fn from_raw(raw: *const Py<T>) -> Self {
-        Self {
-            ptr: unsafe { NonNull::new_unchecked(raw as *mut _) },
-        }
+        unsafe { Self::from_non_null(NonNull::new_unchecked(raw as *mut _)) }
     }
 
     /// Safety: payload type of `obj` must be `T`
diff --git a/vm/src/vm/mod.rs b/vm/src/vm/mod.rs
index 69938975983..b147f8528b7 100644
--- a/vm/src/vm/mod.rs
+++ b/vm/src/vm/mod.rs
@@ -448,19 +448,7 @@ impl VirtualMachine {
         use crate::builtins::PyFunction;
 
         // Create a function object for module code, similar to CPython's PyEval_EvalCode
-        let qualname = self.ctx.new_str(code.obj_name.as_str());
-        let func = PyFunction::new(
-            code.clone(),
-            scope.globals.clone(),
-            None, // closure
-            None, // defaults
-            None, // kwdefaults
-            qualname,
-            self.ctx.new_tuple(vec![]), // type_params
-            self.ctx.new_dict(),        // annotations
-            self.ctx.none(),            // doc
-            self,
-        )?;
+        let func = PyFunction::new(code.clone(), scope.globals.clone(), self)?;
         let func_obj = func.into_ref(&self.ctx).into();
 
         let frame = Frame::new(code, scope, self.builtins.dict(), &[], Some(func_obj), self)