diff --git a/derive/src/pyclass.rs b/derive/src/pyclass.rs
index b26520f60..8ead38119 100644
--- a/derive/src/pyclass.rs
+++ b/derive/src/pyclass.rs
@@ -16,9 +16,63 @@ use syn_ext::ext::*;
 struct ImplContext {
     impl_extend_items: ItemNursery,
     getset_items: GetSetNursery,
+    extend_slots_items: ItemNursery,
     errors: Vec<syn::Error>,
 }
 
+fn extract_items_into_context<'a, Item>(
+    context: &mut ImplContext,
+    items: impl Iterator<Item = &'a mut Item>,
+) where
+    Item: ItemLike + ToTokens + GetIdent + syn_ext::ext::ItemAttrExt + 'a,
+{
+    for item in items {
+        let r = item.try_split_attr_mut(|attrs, item| {
+            let (pyitems, cfgs) = attrs_to_content_items(&attrs, new_impl_item::<Item>)?;
+            for pyitem in pyitems.iter().rev() {
+                let r = pyitem.gen_impl_item(ImplItemArgs::<Item> {
+                    item,
+                    attrs,
+                    context,
+                    cfgs: cfgs.as_slice(),
+                });
+                context.errors.ok_or_push(r);
+            }
+            Ok(())
+        });
+        context.errors.ok_or_push(r);
+    }
+    context.errors.ok_or_push(context.getset_items.validate());
+}
+
+fn raw_extend_methods<T: syn::parse::Parse>(context: &ImplContext) -> impl Iterator<Item = T> {
+    let getset_impl = &context.getset_items;
+    let extend_impl = &context.impl_extend_items;
+    let slots_impl = &context.extend_slots_items;
+    macro_rules! iter_chain {
+        ($($it:expr),*$(,)?) => {
+            std::iter::empty()
+                $(.chain(std::iter::once($it)))*
+        };
+    }
+    iter_chain![
+        parse_quote! {
+            fn __extend_py_class(
+                ctx: &::rustpython_vm::pyobject::PyContext,
+                class: &::rustpython_vm::obj::objtype::PyClassRef,
+            ) {
+                #getset_impl
+                #extend_impl
+            }
+        },
+        parse_quote! {
+            fn __extend_slots(slots: &mut ::rustpython_vm::slots::PyClassSlots) {
+                #slots_impl
+            }
+        },
+    ]
+}
+
 pub(crate) fn impl_pyimpl(
     attr: AttributeArgs,
     item: Item,
@@ -26,80 +80,55 @@ pub(crate) fn impl_pyimpl(
     let mut context = ImplContext::default();
     let mut tokens = match item {
         Item::Impl(mut imp) => {
-            for item in imp.items.iter_mut() {
-                let r = item.try_split_attr_mut(|attrs, item| {
-                    let (pyitems, cfgs) =
-                        attrs_to_content_items(&attrs, new_impl_item::<syn::ImplItem>)?;
-                    for pyitem in pyitems.iter().rev() {
-                        let r = pyitem.gen_impl_item(ImplItemArgs {
-                            item,
-                            attrs,
-                            context: &mut context,
-                            cfgs: cfgs.as_slice(),
-                        });
-                        context.errors.ok_or_push(r);
-                    }
-                    Ok(())
-                });
-                context.errors.ok_or_push(r);
-            }
-            context.errors.ok_or_push(context.getset_items.validate());
+            extract_items_into_context(&mut context, imp.items.iter_mut());
+
+            let ExtractedImplAttrs {
+                with_impl,
+                flags,
+                with_slots,
+                structseq_impl,
+            } = extract_impl_attrs(attr)?;
 
-            let (with_impl, flags) = extract_impl_attrs(attr)?;
             let ty = &imp.self_ty;
-            let getset_impl = &context.getset_items;
-            let extend_impl = &context.impl_extend_items;
-            quote! {
-                #imp
-                impl ::rustpython_vm::pyobject::PyClassImpl for #ty {
-                    const TP_FLAGS: ::rustpython_vm::slots::PyTpFlags = ::rustpython_vm::slots::PyTpFlags::from_bits_truncate(#flags);
 
-                    fn impl_extend_class(
-                        ctx: &::rustpython_vm::pyobject::PyContext,
-                        class: &::rustpython_vm::obj::objtype::PyClassRef,
-                    ) {
-                        #getset_impl
-                        #extend_impl
-                        #with_impl
+            if structseq_impl {
+                imp.items.extend(raw_extend_methods(&context));
+                imp.into_token_stream()
+            } else {
+                let getset_impl = &context.getset_items;
+                let extend_impl = &context.impl_extend_items;
+                let slots_impl = &context.extend_slots_items;
+                quote! {
+                    #imp
+                    impl ::rustpython_vm::pyobject::PyClassImpl for #ty {
+                        const TP_FLAGS: ::rustpython_vm::slots::PyTpFlags = ::rustpython_vm::slots::PyTpFlags::from_bits_truncate(#flags);
+
+                        fn impl_extend_class(
+                            ctx: &::rustpython_vm::pyobject::PyContext,
+                            class: &::rustpython_vm::obj::objtype::PyClassRef,
+                        ) {
+                            #getset_impl
+                            #extend_impl
+                            #with_impl
+                        }
+
+                        fn extend_slots(slots: &mut ::rustpython_vm::slots::PyClassSlots) {
+                            #with_slots
+                            #slots_impl
+                        }
                     }
                 }
             }
         }
         Item::Trait(mut trai) => {
             let mut context = ImplContext::default();
-            for item in trai.items.iter_mut() {
-                let r = item.try_split_attr_mut(|attrs, item| {
-                    let (pyitems, cfgs) =
-                        attrs_to_content_items(&attrs, new_impl_item::<syn::TraitItem>)?;
-                    for pyitem in pyitems.iter().rev() {
-                        let r = pyitem.gen_impl_item(ImplItemArgs {
-                            item,
-                            attrs,
-                            context: &mut context,
-                            cfgs: cfgs.as_slice(),
-                        });
-                        context.errors.ok_or_push(r);
-                    }
-                    Ok(())
-                });
-                context.errors.ok_or_push(r);
-            }
-            context.errors.ok_or_push(context.getset_items.validate());
+            extract_items_into_context(&mut context, trai.items.iter_mut());
+
+            trai.items.extend(raw_extend_methods(&context));
 
-            let getset_impl = &context.getset_items;
-            let extend_impl = &context.impl_extend_items;
-            trai.items.push(parse_quote! {
-                fn __extend_py_class(
-                    ctx: &::rustpython_vm::pyobject::PyContext,
-                    class: &::rustpython_vm::obj::objtype::PyClassRef,
-                ) {
-                    #getset_impl
-                    #extend_impl
-                }
-            });
             trai.into_token_stream()
         }
-        item => quote!(#item),
+        item => item.into_token_stream(),
     };
     if let Some(error) = context.errors.into_error() {
         let error = Diagnostic::from(error);
@@ -161,6 +190,19 @@ pub(crate) fn impl_pyclass(
     Ok(ret)
 }
 
+struct StructSeqItemMeta(ItemMetaInner);
+
+impl ItemMeta for StructSeqItemMeta {
+    const ALLOWED_NAMES: &'static [&'static str] = &["module", "name", "with_pyimpl"];
+
+    fn from_inner(inner: ItemMetaInner) -> Self {
+        Self(inner)
+    }
+    fn inner(&self) -> &ItemMetaInner {
+        &self.0
+    }
+}
+
 pub(crate) fn impl_pystruct_sequence(
     attr: AttributeArgs,
     item: Item,
@@ -174,7 +216,9 @@ pub(crate) fn impl_pystruct_sequence(
         )
     };
     let fake_ident = Ident::new("pystruct_sequence", struc.span());
-    let class_meta = ClassItemMeta::from_nested(struc.ident.clone(), fake_ident, attr.into_iter())?;
+    let meta = StructSeqItemMeta::from_nested(struc.ident.clone(), fake_ident, attr.into_iter())?;
+    let with_pyimpl = meta.inner()._bool("with_pyimpl")?;
+    let class_meta = ClassItemMeta(meta.0);
     let class_name = class_meta.class_name()?;
     let module_name = class_meta.mandatory_module()?;
 
@@ -206,6 +250,19 @@ pub(crate) fn impl_pystruct_sequence(
         }
     }
 
+    let (with_extend, with_slots) = if with_pyimpl {
+        (
+            quote! {
+                Self::__extend_py_class(ctx, class);
+            },
+            quote! {
+                Self::__extend_slots(slots);
+            },
+        )
+    } else {
+        (quote! {}, quote! {})
+    };
+
     let ty = &struc.ident;
     let ret = quote! {
         #struc
@@ -242,6 +299,7 @@ pub(crate) fn impl_pystruct_sequence(
 
                 #(#properties)*
                 class.set_str_attr("__repr__", ctx.new_method(Self::repr));
+                #with_extend
             }
 
             fn make_class(
@@ -250,6 +308,10 @@ pub(crate) fn impl_pystruct_sequence(
                 use crate::pyobject::PyClassDef;
                 Self::make_class_with_base(ctx, Self::NAME,  &ctx.types.tuple_type)
             }
+
+            fn extend_slots(slots: &mut ::rustpython_vm::slots::PyClassSlots) {
+                #with_slots
+            }
         }
     };
     Ok(ret)
@@ -394,11 +456,11 @@ where
                 #transform(Self::#ident)
             };
             quote! {
-                (*class.slots.write()).#slot_ident = Some(#into_func);
+                slots.#slot_ident = Some(#into_func);
             }
         };
 
-        args.context.impl_extend_items.add_item(
+        args.context.extend_slots_items.add_item(
             format!("(slot {})", slot_name),
             args.cfgs.to_vec(),
             tokens,
@@ -639,11 +701,18 @@ impl SlotItemMeta {
     }
 }
 
-fn extract_impl_attrs(
-    attr: AttributeArgs,
-) -> std::result::Result<(TokenStream, TokenStream), Diagnostic> {
+struct ExtractedImplAttrs {
+    with_impl: TokenStream,
+    with_slots: TokenStream,
+    flags: TokenStream,
+    structseq_impl: bool,
+}
+
+fn extract_impl_attrs(attr: AttributeArgs) -> std::result::Result<ExtractedImplAttrs, Diagnostic> {
     let mut withs = Vec::new();
+    let mut with_slots = Vec::new();
     let mut flags = vec![quote! { ::rustpython_vm::slots::PyTpFlags::DEFAULT.bits() }];
+    let mut structseq_impl = false;
     #[cfg(debug_assertions)]
     {
         flags.push(quote! {
@@ -658,9 +727,21 @@ fn extract_impl_attrs(
                     for meta in nested {
                         match meta {
                             NestedMeta::Meta(Meta::Path(path)) => {
-                                withs.push(quote! {
-                                    <Self as #path>::__extend_py_class(ctx, class);
-                                });
+                                if path_eq(&path, "Self") {
+                                    withs.push(quote! {
+                                        Self::__extend_py_class(ctx, class);
+                                    });
+                                    with_slots.push(quote! {
+                                        Self::__extend_slots(slots);
+                                    });
+                                } else {
+                                    withs.push(quote! {
+                                        <Self as #path>::__extend_py_class(ctx, class);
+                                    });
+                                    with_slots.push(quote! {
+                                        <Self as #path>::__extend_slots(slots);
+                                    });
+                                }
                             }
                             meta => {
                                 bail_span!(meta, "#[pyimpl(with(...))] arguments should be paths")
@@ -691,18 +772,25 @@ fn extract_impl_attrs(
                     bail_span!(path, "Unknown pyimpl attribute")
                 }
             }
+            NestedMeta::Meta(Meta::Path(path)) if path_eq(&path, "structseq_impl") => {
+                structseq_impl = true
+            }
             attr => bail_span!(attr, "Unknown pyimpl attribute"),
         }
     }
 
-    Ok((
-        quote! {
+    Ok(ExtractedImplAttrs {
+        with_impl: quote! {
             #(#withs)*
         },
-        quote! {
+        flags: quote! {
             #(#flags)*
         },
-    ))
+        with_slots: quote! {
+            #(#with_slots)*
+        },
+        structseq_impl,
+    })
 }
 
 fn new_impl_item<Item>(index: usize, attr_name: String) -> Box<dyn ImplItem<Item>>
diff --git a/derive/src/util.rs b/derive/src/util.rs
index 0759ce91a..59e028cd3 100644
--- a/derive/src/util.rs
+++ b/derive/src/util.rs
@@ -223,7 +223,7 @@ impl ItemMeta for SimpleItemMeta {
     }
 }
 
-pub(crate) struct ClassItemMeta(ItemMetaInner);
+pub(crate) struct ClassItemMeta(pub ItemMetaInner);
 
 impl ItemMeta for ClassItemMeta {
     const ALLOWED_NAMES: &'static [&'static str] = &["module", "name"];
diff --git a/vm/src/exceptions.rs b/vm/src/exceptions.rs
index f1bebec9d..bf989ea8d 100644
--- a/vm/src/exceptions.rs
+++ b/vm/src/exceptions.rs
@@ -10,7 +10,7 @@ use crate::pyobject::{
     BorrowValue, PyClassDef, PyClassImpl, PyContext, PyIterable, PyObjectRef, PyRef, PyResult,
     PyValue, TryFromObject, TypeProtocol,
 };
-use crate::types::create_type_with_flags;
+use crate::types::create_type_with_slots;
 use crate::VirtualMachine;
 use crate::{py_serde, sysmodule};
 
@@ -463,7 +463,7 @@ pub struct ExceptionZoo {
 impl ExceptionZoo {
     pub fn new(type_type: &PyClassRef, object_type: &PyClassRef) -> Self {
         let create_exception_type = |name: &str, base: &PyClassRef| {
-            create_type_with_flags(name, type_type, base, PyBaseException::TP_FLAGS)
+            create_type_with_slots(name, type_type, base, PyBaseException::make_slots())
         };
         // Sorted By Hierarchy then alphabetized.
         let base_exception_type = create_exception_type(PyBaseExceptionRef::NAME, &object_type);
diff --git a/vm/src/macros.rs b/vm/src/macros.rs
index 9349c7c09..cb5d7bc6e 100644
--- a/vm/src/macros.rs
+++ b/vm/src/macros.rs
@@ -38,30 +38,35 @@ macro_rules! py_class {
     };
     ( $ctx:expr, $class_name:expr, $class_base:expr, $flags:expr, { $($name:tt => $value:expr),* $(,)* }) => {
         {
-            let py_class = $ctx.new_class($class_name, $class_base, $crate::slots::PyTpFlags::DEFAULT | $flags);
-            $crate::extend_class!($ctx, &py_class, { $($name => $value),* });
+            #[allow(unused_mut)]
+            let mut slots: $crate::slots::PyClassSlots = ($crate::slots::PyTpFlags::DEFAULT | $flags).into();
+            $($crate::py_class!(@extract_slots($ctx, &mut slots, $name, $value));)*
+            let py_class = $ctx.new_class($class_name, $class_base, slots);
+            $($crate::py_class!(@extract_attrs($ctx, &py_class, $name, $value));)*
+            $ctx.add_tp_new_wrapper(&py_class);
             py_class
         }
     };
+    (@extract_slots($ctx:expr, $slots:expr, (slot $slot_name:ident), $value:expr)) => {
+        $slots.$slot_name = Some(
+            $crate::function::IntoPyNativeFunc::into_func($value)
+        );
+    };
+    (@extract_slots($ctx:expr, $class:expr, $name:expr, $value:expr)) => {};
+    (@extract_attrs($ctx:expr, $slots:expr, (slot $slot_name:ident), $value:expr)) => {};
+    (@extract_attrs($ctx:expr, $class:expr, $name:expr, $value:expr)) => {
+        $class.set_str_attr($name, $value);
+    };
 }
 
 #[macro_export]
 macro_rules! extend_class {
-    ( $ctx:expr, $class:expr, { $($name:tt => $value:expr),* $(,)* }) => {
+    ( $ctx:expr, $class:expr, { $($name:expr => $value:expr),* $(,)* }) => {
         $(
-            $crate::extend_class!(@set_attr($ctx, $class, $name, $value));
+            $class.set_str_attr($name, $value);
         )*
         $ctx.add_tp_new_wrapper(&$class);
     };
-
-    (@set_attr($ctx:expr, $class:expr, (slot $slot_name:ident), $value:expr)) => {
-        $class.slots.write().$slot_name = Some(
-            $crate::function::IntoPyNativeFunc::into_func($value)
-        );
-    };
-    (@set_attr($ctx:expr, $class:expr, $name:expr, $value:expr)) => {
-        $class.set_str_attr($name, $value);
-    };
 }
 
 #[macro_export]
diff --git a/vm/src/obj/objmodule.rs b/vm/src/obj/objmodule.rs
index 5646ac624..e156e424c 100644
--- a/vm/src/obj/objmodule.rs
+++ b/vm/src/obj/objmodule.rs
@@ -56,6 +56,7 @@ impl PyModuleRef {
         vm: &VirtualMachine,
     ) -> PyResult<()> {
         debug_assert!(crate::pyobject::TypeProtocol::lease_class(self.as_object())
+            .slots
             .flags
             .has_feature(crate::slots::PyTpFlags::HAS_DICT));
         init_module_dict(
diff --git a/vm/src/obj/objtype.rs b/vm/src/obj/objtype.rs
index 70b618a44..da3b62798 100644
--- a/vm/src/obj/objtype.rs
+++ b/vm/src/obj/objtype.rs
@@ -32,8 +32,7 @@ pub struct PyClass {
     pub mro: Vec<PyClassRef>,
     pub subclasses: PyRwLock<Vec<PyWeak>>,
     pub attributes: PyRwLock<PyAttributes>,
-    pub flags: PyTpFlags,
-    pub slots: PyRwLock<PyClassSlots>,
+    pub slots: PyClassSlots,
 }
 
 impl fmt::Display for PyClass {
@@ -58,7 +57,7 @@ impl PyValue for PyClass {
 
 impl PyClassRef {
     fn tp_name(zelf: Self, vm: &VirtualMachine) -> String {
-        let opt_name = zelf.slots.read().name.clone();
+        let opt_name = zelf.slots.name.read().clone();
         opt_name.unwrap_or_else(|| {
             let module = zelf.attributes.read().get("__module__").cloned();
             let new_name = if let Some(module) = module {
@@ -69,7 +68,7 @@ impl PyClassRef {
             } else {
                 zelf.name.clone()
             };
-            zelf.slots.write().name = Some(new_name.clone());
+            *zelf.slots.name.write() = Some(new_name.clone());
             new_name
         })
     }
@@ -104,7 +103,7 @@ impl PyClassRef {
 
     #[pyproperty(magic)]
     fn flags(self) -> u64 {
-        self.flags.bits()
+        self.slots.flags.bits()
     }
 
     #[pymethod(magic)]
@@ -158,7 +157,7 @@ impl PyClassRef {
 
     #[pyproperty(magic, setter)]
     fn set_module(self, value: PyObjectRef) {
-        self.slots.write().name = None;
+        *self.slots.name.write() = None;
         self.attributes
             .write()
             .insert("__module__".to_owned(), value);
@@ -188,7 +187,7 @@ impl PyClassRef {
 
         if let Some(attr) = self.get_attr(&name) {
             let attr_class = attr.class();
-            let slots = attr_class.slots.read();
+            let slots = &attr_class.slots;
             if let Some(ref descr_get) = slots.descr_get {
                 drop(mcl);
                 return descr_get(vm, attr, None, OptionalArg::Present(self.into_object()));
@@ -321,12 +320,10 @@ impl PyClassRef {
             let winner = calculate_meta_class(metatype.clone(), &bases, vm)?;
             let metatype = if !winner.is(&metatype) {
                 #[allow(clippy::redundant_clone)] // false positive
-                {
-                    if let Some(ref tp_new) = winner.clone().slots.read().new {
-                        // Pass it to the winner
+                if let Some(ref tp_new) = winner.clone().slots.new {
+                    // Pass it to the winner
 
-                        return tp_new(vm, args.insert(winner.into_object()));
-                    }
+                    return tp_new(vm, args.insert(winner.into_object()));
                 }
                 winner
             } else {
@@ -360,7 +357,7 @@ impl PyClassRef {
         }
 
         // TODO: how do we know if it should have a dict?
-        let flags = base.flags | PyTpFlags::HAS_DICT;
+        let flags = base.slots.flags | PyTpFlags::HAS_DICT;
 
         let typ = new(
             metatype,
@@ -368,7 +365,7 @@ impl PyClassRef {
             base,
             bases,
             attributes,
-            flags,
+            flags.into(),
         )
         .map_err(|e| vm.new_type_error(e))?;
 
@@ -544,7 +541,7 @@ fn call_tp_new(
                 return vm.invoke(&new_meth, args.insert(typ.clone().into_object()));
             }
         }
-        if let Some(tp_new) = cls.slots.read().new.as_ref() {
+        if let Some(tp_new) = cls.slots.new.as_ref() {
             return tp_new(vm, args.insert(subtype.into_object()));
         }
     }
@@ -677,7 +674,7 @@ pub fn new(
     base: PyClassRef,
     bases: Vec<PyClassRef>,
     attrs: HashMap<String, PyObjectRef>,
-    mut flags: PyTpFlags,
+    mut slots: PyClassSlots,
 ) -> Result<PyClassRef, String> {
     // Check for duplicates in bases.
     let mut unique_bases = HashSet::new();
@@ -693,8 +690,8 @@ pub fn new(
         .collect();
     let mro = linearise_mro(mros)?;
 
-    if base.flags.has_feature(PyTpFlags::HAS_DICT) {
-        flags |= PyTpFlags::HAS_DICT
+    if base.slots.flags.has_feature(PyTpFlags::HAS_DICT) {
+        slots.flags |= PyTpFlags::HAS_DICT
     }
     let new_type = PyRef::new_ref(
         PyClass {
@@ -704,8 +701,7 @@ pub fn new(
             mro,
             subclasses: PyRwLock::default(),
             attributes: PyRwLock::new(attrs),
-            flags,
-            slots: PyRwLock::default(),
+            slots,
         },
         typ,
         None,
@@ -763,7 +759,7 @@ fn best_base<'a>(bases: &'a [PyClassRef], vm: &VirtualMachine) -> PyResult<PyCla
         //         return NULL;
         // }
 
-        if !base_i.flags.has_feature(PyTpFlags::BASETYPE) {
+        if !base_i.slots.flags.has_feature(PyTpFlags::BASETYPE) {
             return Err(vm.new_type_error(format!(
                 "type '{}' is not an acceptable base type",
                 base_i.name
diff --git a/vm/src/pyobject.rs b/vm/src/pyobject.rs
index 07b41c653..c5759f7b0 100644
--- a/vm/src/pyobject.rs
+++ b/vm/src/pyobject.rs
@@ -36,8 +36,8 @@ use crate::obj::objstr;
 use crate::obj::objtuple::{PyTuple, PyTupleRef};
 use crate::obj::objtype::{self, PyClass, PyClassRef};
 use crate::scope::Scope;
-use crate::slots::PyTpFlags;
-use crate::types::{create_type, create_type_with_flags, initialize_types, TypeZoo};
+use crate::slots::{PyClassSlots, PyTpFlags};
+use crate::types::{create_type, create_type_with_slots, initialize_types, TypeZoo};
 use crate::vm::VirtualMachine;
 use rustpython_common::cell::{PyRwLock, PyRwLockReadGuard};
 use rustpython_common::rc::PyRc;
@@ -276,8 +276,8 @@ impl PyContext {
             .unwrap()
     }
 
-    pub fn new_class(&self, name: &str, base: &PyClassRef, flags: PyTpFlags) -> PyClassRef {
-        create_type_with_flags(name, &self.types.type_type, base, flags)
+    pub fn new_class(&self, name: &str, base: &PyClassRef, slots: PyClassSlots) -> PyClassRef {
+        create_type_with_slots(name, &self.types.type_type, base, slots)
     }
 
     pub fn new_namespace(&self) -> PyObjectRef {
@@ -1177,7 +1177,7 @@ pub trait PyValue: fmt::Debug + PyThreadingConstraint + Sized + 'static {
     }
 
     fn into_ref_with_type_unchecked(self, cls: PyClassRef, vm: &VirtualMachine) -> PyRef<Self> {
-        let dict = if cls.flags.has_feature(PyTpFlags::HAS_DICT) {
+        let dict = if cls.slots.flags.has_feature(PyTpFlags::HAS_DICT) {
             Some(vm.ctx.new_dict())
         } else {
             None
@@ -1282,7 +1282,7 @@ pub trait PyClassImpl: PyClassDef {
     fn extend_class(ctx: &PyContext, class: &PyClassRef) {
         #[cfg(debug_assertions)]
         {
-            assert!(class.flags.is_created_with_flags());
+            assert!(class.slots.flags.is_created_with_flags());
         }
         if Self::TP_FLAGS.has_feature(PyTpFlags::HAS_DICT) {
             class.set_str_attr(
@@ -1295,7 +1295,6 @@ pub trait PyClassImpl: PyClassDef {
             );
         }
         Self::impl_extend_class(ctx, class);
-        class.slots.write().name = Some(Self::TP_NAME.to_owned());
         ctx.add_tp_new_wrapper(&class);
         if let Some(doc) = Self::DOC {
             class.set_str_attr("__doc__", ctx.new_str(doc));
@@ -1310,13 +1309,23 @@ pub trait PyClassImpl: PyClassDef {
     }
 
     fn make_class_with_base(ctx: &PyContext, name: &str, base: &PyClassRef) -> PyClassRef {
-        let py_class = ctx.new_class(name, base, Self::TP_FLAGS);
+        let py_class = ctx.new_class(name, base, Self::make_slots());
         Self::extend_class(ctx, &py_class);
         py_class
     }
 
     fn create_bare_type(type_type: &PyClassRef, base: &PyClassRef) -> PyClassRef {
-        create_type_with_flags(Self::NAME, type_type, base, Self::TP_FLAGS)
+        create_type_with_slots(Self::NAME, type_type, base, Self::make_slots())
+    }
+
+    fn extend_slots(slots: &mut PyClassSlots);
+
+    fn make_slots() -> PyClassSlots {
+        let mut slots = PyClassSlots::default();
+        slots.flags = Self::TP_FLAGS;
+        slots.name = PyRwLock::new(Some(Self::TP_NAME.to_owned()));
+        Self::extend_slots(&mut slots);
+        slots
     }
 }
 
diff --git a/vm/src/slots.rs b/vm/src/slots.rs
index a4653c7b9..345b1d099 100644
--- a/vm/src/slots.rs
+++ b/vm/src/slots.rs
@@ -1,3 +1,4 @@
+use crate::common::cell::PyRwLock;
 use crate::function::{OptionalArg, PyFuncArgs, PyNativeFunc};
 use crate::pyobject::{IdProtocol, PyObjectRef, PyRef, PyResult, PyValue, TryFromObject};
 use crate::VirtualMachine;
@@ -35,12 +36,22 @@ impl Default for PyTpFlags {
 
 #[derive(Default)]
 pub struct PyClassSlots {
-    pub name: Option<String>, // tp_name, not class name
+    pub flags: PyTpFlags,
+    pub name: PyRwLock<Option<String>>, // tp_name, not class name
     pub new: Option<PyNativeFunc>,
     pub call: Option<PyNativeFunc>,
     pub descr_get: Option<PyDescrGetFunc>,
 }
 
+impl From<PyTpFlags> for PyClassSlots {
+    fn from(flags: PyTpFlags) -> Self {
+        Self {
+            flags,
+            ..Default::default()
+        }
+    }
+}
+
 impl std::fmt::Debug for PyClassSlots {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.write_str("PyClassSlots")
diff --git a/vm/src/stdlib/time_module.rs b/vm/src/stdlib/time_module.rs
index 936be534e..3184ef97e 100644
--- a/vm/src/stdlib/time_module.rs
+++ b/vm/src/stdlib/time_module.rs
@@ -170,7 +170,7 @@ fn time_strptime(
     Ok(PyStructTime::new(vm, instant, -1).into_obj(vm))
 }
 
-#[pystruct_sequence(module = "time", name = "struct_time")]
+#[pystruct_sequence(with_pyimpl, module = "time", name = "struct_time")]
 #[allow(dead_code)]
 struct PyStructTime {
     tm_year: PyObjectRef,
@@ -190,6 +190,7 @@ impl fmt::Debug for PyStructTime {
     }
 }
 
+#[pyimpl(structseq_impl)]
 impl PyStructTime {
     fn new(vm: &VirtualMachine, tm: NaiveDateTime, isdst: i32) -> Self {
         PyStructTime {
@@ -227,6 +228,7 @@ impl PyStructTime {
             .into_object()
     }
 
+    #[pyslot]
     fn tp_new(cls: PyClassRef, seq: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyTupleRef> {
         Self::try_from_object(vm, seq)?.into_struct_sequence(vm, cls)
     }
@@ -260,11 +262,6 @@ pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
 
     let struct_time_type = PyStructTime::make_class(ctx);
 
-    // TODO: allow $[pyimpl]s for struct_sequences
-    extend_class!(ctx, struct_time_type, {
-        (slot new) => PyStructTime::tp_new,
-    });
-
     py_module!(vm, "time", {
         "asctime" => ctx.new_function(time_asctime),
         "ctime" => ctx.new_function(time_ctime),
diff --git a/vm/src/sysmodule.rs b/vm/src/sysmodule.rs
index fee1c93eb..12a41a31f 100644
--- a/vm/src/sysmodule.rs
+++ b/vm/src/sysmodule.rs
@@ -69,7 +69,7 @@ fn getframe(offset: OptionalArg<usize>, vm: &VirtualMachine) -> PyResult<FrameRe
 /// sys.flags
 ///
 /// Flags provided through command line arguments or environment vars.
-#[pystruct_sequence(name = "flags", module = "sys")]
+#[pystruct_sequence(with_pyimpl, name = "flags", module = "sys")]
 #[derive(Default, Debug)]
 struct SysFlags {
     /// -d
@@ -104,6 +104,7 @@ struct SysFlags {
     utf8_mode: u8,
 }
 
+#[pyimpl(structseq_impl)]
 impl SysFlags {
     fn from_settings(settings: &PySettings) -> Self {
         // Start with sensible defaults:
@@ -119,6 +120,11 @@ impl SysFlags {
         flags.dont_write_bytecode = settings.dont_write_bytecode as u8;
         flags
     }
+
+    #[pyslot]
+    fn tp_new(_cls: PyClassRef, _args: PyFuncArgs, vm: &VirtualMachine) -> PyResult {
+        Err(vm.new_type_error("cannot create 'sys.flags' instances".to_owned()))
+    }
 }
 
 fn sys_getrefcount(obj: PyObjectRef) -> usize {
@@ -433,21 +439,11 @@ pub fn make_module(vm: &VirtualMachine, module: PyObjectRef, builtins: PyObjectR
     let ctx = &vm.ctx;
 
     let flags_type = SysFlags::make_class(ctx);
-    extend_class!(ctx, flags_type, {
-      (slot new) => |_cls: PyClassRef, _args: PyFuncArgs, vm: &VirtualMachine| -> PyResult {
-        Err(vm.new_type_error("cannot create 'sys.flags' instances".to_owned()))
-      },
-    });
     let flags = SysFlags::from_settings(&vm.state.settings)
         .into_struct_sequence(vm, flags_type)
         .unwrap();
 
     let version_info_type = version::VersionInfo::make_class(ctx);
-    extend_class!(ctx, version_info_type, {
-      (slot new) => |_cls: PyClassRef, _args: PyFuncArgs, vm: &VirtualMachine| -> PyResult {
-        Err(vm.new_type_error("cannot create 'sys.version_info' instances".to_owned()))
-      },
-    });
     let version_info = version::VersionInfo::VERSION
         .into_struct_sequence(vm, version_info_type)
         .unwrap();
diff --git a/vm/src/types.rs b/vm/src/types.rs
index 41393d069..5bf28904a 100644
--- a/vm/src/types.rs
+++ b/vm/src/types.rs
@@ -40,7 +40,7 @@ use crate::obj::objweakproxy;
 use crate::obj::objweakref;
 use crate::obj::objzip;
 use crate::pyobject::{PyAttributes, PyClassDef, PyClassImpl, PyContext, PyObject};
-use crate::slots::PyTpFlags;
+use crate::slots::PyClassSlots;
 use rustpython_common::{cell::PyRwLock, rc::PyRc};
 use std::mem::MaybeUninit;
 use std::ptr;
@@ -202,14 +202,14 @@ impl TypeZoo {
 }
 
 pub fn create_type(name: &str, type_type: &PyClassRef, base: &PyClassRef) -> PyClassRef {
-    create_type_with_flags(name, type_type, base, Default::default())
+    create_type_with_slots(name, type_type, base, Default::default())
 }
 
-pub fn create_type_with_flags(
+pub fn create_type_with_slots(
     name: &str,
     type_type: &PyClassRef,
     base: &PyClassRef,
-    flags: PyTpFlags,
+    slots: PyClassSlots,
 ) -> PyClassRef {
     let dict = PyAttributes::new();
     objtype::new(
@@ -218,7 +218,7 @@ pub fn create_type_with_flags(
         base.clone(),
         vec![base.clone()],
         dict,
-        PyTpFlags::default() | flags,
+        slots,
     )
     .expect("Failed to create a new type in internal code.")
 }
@@ -265,8 +265,7 @@ fn init_type_hierarchy() -> (PyClassRef, PyClassRef) {
                     mro: vec![],
                     subclasses: PyRwLock::default(),
                     attributes: PyRwLock::new(PyAttributes::new()),
-                    flags: objtype::PyClassRef::TP_FLAGS,
-                    slots: PyRwLock::default(),
+                    slots: objtype::PyClassRef::make_slots(),
                 },
             },
             Uninit { typ }
@@ -281,8 +280,7 @@ fn init_type_hierarchy() -> (PyClassRef, PyClassRef) {
                     mro: vec![],
                     subclasses: PyRwLock::default(),
                     attributes: PyRwLock::new(PyAttributes::new()),
-                    flags: objobject::PyBaseObject::TP_FLAGS,
-                    slots: PyRwLock::default(),
+                    slots: objobject::PyBaseObject::make_slots(),
                 },
             },
             Uninit { typ },
diff --git a/vm/src/version.rs b/vm/src/version.rs
index 66c2d5fa1..ad1a17128 100644
--- a/vm/src/version.rs
+++ b/vm/src/version.rs
@@ -15,7 +15,7 @@ const SERIAL: usize = 0;
 pub const VERSION_HEX: usize =
     (MAJOR << 24) | (MINOR << 16) | (MICRO << 8) | (RELEASELEVEL_N << 4) | SERIAL;
 
-#[pystruct_sequence(module = "sys", name = "version_info")]
+#[pystruct_sequence(with_pyimpl, module = "sys", name = "version_info")]
 #[derive(Default, Debug)]
 pub struct VersionInfo {
     major: usize,
@@ -34,6 +34,7 @@ pub fn get_version() -> String {
     )
 }
 
+#[pyimpl(structseq_impl)]
 impl VersionInfo {
     pub const VERSION: VersionInfo = VersionInfo {
         major: MAJOR,
@@ -42,6 +43,14 @@ impl VersionInfo {
         releaselevel: RELEASELEVEL,
         serial: SERIAL,
     };
+    #[pyslot]
+    fn tp_new(
+        _cls: crate::obj::objtype::PyClassRef,
+        _args: crate::function::PyFuncArgs,
+        vm: &crate::VirtualMachine,
+    ) -> crate::pyobject::PyResult {
+        Err(vm.new_type_error("cannot create 'sys.version_info' instances".to_owned()))
+    }
 }
 
 pub fn get_version_number() -> String {
diff --git a/vm/src/vm.rs b/vm/src/vm.rs
index de6020304..1f12888f7 100644
--- a/vm/src/vm.rs
+++ b/vm/src/vm.rs
@@ -767,7 +767,7 @@ impl VirtualMachine {
         cls: Option<PyObjectRef>,
     ) -> Option<PyResult> {
         let descr_class = descr.class();
-        let slots = descr_class.slots.read();
+        let slots = &descr_class.slots;
         if let Some(descr_get) = slots.descr_get.as_ref() {
             Some(descr_get(self, descr, obj, OptionalArg::from_option(cls)))
         } else if let Some(ref descriptor) = descr_class.get_attr("__get__") {
@@ -819,7 +819,7 @@ impl VirtualMachine {
 
     fn _invoke(&self, callable: &PyObjectRef, args: PyFuncArgs) -> PyResult {
         vm_trace!("Invoke: {:?} {:?}", callable, args);
-        if let Some(slot_call) = callable.lease_class().slots.read().call.as_ref() {
+        if let Some(slot_call) = callable.lease_class().slots.call.as_ref() {
             self.trace_event(TraceEvent::Call)?;
             let args = args.insert(callable.clone());
             let result = slot_call(self, args);
@@ -1052,8 +1052,7 @@ impl VirtualMachine {
 
     pub fn is_callable(&self, obj: &PyObjectRef) -> bool {
         let class = obj.lease_class();
-        let lock = class.slots.read();
-        lock.call.is_some() || class.has_attr("__call__")
+        class.slots.call.is_some() || class.has_attr("__call__")
     }
 
     #[inline]