diff --git a/src/README.md b/src/README.md
index 57d41a6be89995..123bd0a7e9250b 100644
--- a/src/README.md
+++ b/src/README.md
@@ -126,9 +126,9 @@ Typical ways of working with internal fields are:
 * `obj->GetInternalField(i)` to get a JavaScript value from an internal field.
 * `obj->SetInternalField(i, v)` to store a JavaScript value in an
   internal field.
-* `obj->GetAlignedPointerFromInternalField(i)` to get a `void*` pointer from an
+* `obj->GetAlignedPointerFromInternalField(i, 0)` to get a `void*` pointer from an
   internal field.
-* `obj->SetAlignedPointerInInternalField(i, p)` to store a `void*` pointer in an
+* `obj->SetAlignedPointerInInternalField(i, p, 0)` to store a `void*` pointer in an
   internal field.
 
 [`Context`][]s provide the same feature under the name “embedder data”.
diff --git a/src/base_object-inl.h b/src/base_object-inl.h
index 68d45487b3f138..cdb086fb1e92c4 100644
--- a/src/base_object-inl.h
+++ b/src/base_object-inl.h
@@ -76,7 +76,7 @@ bool BaseObject::IsBaseObject(IsolateData* isolate_data,
   }
 
   uint16_t* ptr = static_cast<uint16_t*>(
-      obj->GetAlignedPointerFromInternalField(BaseObject::kEmbedderType));
+      obj->GetAlignedPointerFromInternalField(BaseObject::kEmbedderType, 0));
   return ptr == isolate_data->embedder_id_for_non_cppgc();
 }
 
@@ -84,21 +84,21 @@ void BaseObject::TagBaseObject(IsolateData* isolate_data,
                                v8::Local<v8::Object> object) {
   DCHECK_GE(object->InternalFieldCount(), BaseObject::kInternalFieldCount);
   object->SetAlignedPointerInInternalField(
-      BaseObject::kEmbedderType, isolate_data->embedder_id_for_non_cppgc());
+      BaseObject::kEmbedderType, isolate_data->embedder_id_for_non_cppgc(), 0);
 }
 
 void BaseObject::SetInternalFields(IsolateData* isolate_data,
                                    v8::Local<v8::Object> object,
                                    void* slot) {
   TagBaseObject(isolate_data, object);
-  object->SetAlignedPointerInInternalField(BaseObject::kSlot, slot);
+  object->SetAlignedPointerInInternalField(BaseObject::kSlot, slot, 0);
 }
 
 BaseObject* BaseObject::FromJSObject(v8::Local<v8::Value> value) {
   v8::Local<v8::Object> obj = value.As<v8::Object>();
   DCHECK_GE(obj->InternalFieldCount(), BaseObject::kInternalFieldCount);
   return static_cast<BaseObject*>(
-      obj->GetAlignedPointerFromInternalField(BaseObject::kSlot));
+      obj->GetAlignedPointerFromInternalField(BaseObject::kSlot, 0));
 }
 
 template <typename T>
diff --git a/src/base_object.cc b/src/base_object.cc
index 404e2aa8c88d0c..7515a0c93da639 100644
--- a/src/base_object.cc
+++ b/src/base_object.cc
@@ -45,7 +45,7 @@ BaseObject::~BaseObject() {
 
   {
     HandleScope handle_scope(realm()->isolate());
-    object()->SetAlignedPointerInInternalField(BaseObject::kSlot, nullptr);
+    object()->SetAlignedPointerInInternalField(BaseObject::kSlot, nullptr, 0);
   }
 }
 
diff --git a/src/cppgc_helpers-inl.h b/src/cppgc_helpers-inl.h
index 330af7a383058c..0e52bf5a6f4837 100644
--- a/src/cppgc_helpers-inl.h
+++ b/src/cppgc_helpers-inl.h
@@ -19,8 +19,8 @@ void CppgcMixin::Wrap(T* ptr, Realm* realm, v8::Local<v8::Object> obj) {
   v8::Object::Wrap<v8::CppHeapPointerTag::kDefaultTag>(isolate, obj, wrappable);
   // Keep the layout consistent with BaseObjects.
   obj->SetAlignedPointerInInternalField(
-      kEmbedderType, realm->isolate_data()->embedder_id_for_cppgc());
-  obj->SetAlignedPointerInInternalField(kSlot, ptr);
+      kEmbedderType, realm->isolate_data()->embedder_id_for_cppgc(), 0);
+  obj->SetAlignedPointerInInternalField(kSlot, ptr, 0);
   realm->TrackCppgcWrapper(ptr);
 }
 
@@ -41,7 +41,7 @@ T* CppgcMixin::Unwrap(v8::Local<v8::Object> obj) {
   if (obj->InternalFieldCount() != T::kInternalFieldCount) {
     return nullptr;
   }
-  T* ptr = static_cast<T*>(obj->GetAlignedPointerFromInternalField(T::kSlot));
+  T* ptr = static_cast<T*>(obj->GetAlignedPointerFromInternalField(T::kSlot, 0));
   return ptr;
 }
 
diff --git a/src/env-inl.h b/src/env-inl.h
index e790a5cf551895..76fccf1e9fc9fa 100644
--- a/src/env-inl.h
+++ b/src/env-inl.h
@@ -198,7 +198,7 @@ inline Environment* Environment::GetCurrent(v8::Local<v8::Context> context) {
   }
   return static_cast<Environment*>(
       context->GetAlignedPointerFromEmbedderData(
-          ContextEmbedderIndex::kEnvironment));
+          ContextEmbedderIndex::kEnvironment, 0));
 }
 
 inline Environment* Environment::GetCurrent(
diff --git a/src/env.cc b/src/env.cc
index 13ec0d759166df..1c037a2f2424c8 100644
--- a/src/env.cc
+++ b/src/env.cc
@@ -674,12 +674,12 @@ void Environment::AssignToContext(Local<v8::Context> context,
                                   Realm* realm,
                                   const ContextInfo& info) {
   context->SetAlignedPointerInEmbedderData(ContextEmbedderIndex::kEnvironment,
-                                           this);
-  context->SetAlignedPointerInEmbedderData(ContextEmbedderIndex::kRealm, realm);
+                                           this, 0);
+  context->SetAlignedPointerInEmbedderData(ContextEmbedderIndex::kRealm, realm, 0);
 
   // ContextifyContexts will update this to a pointer to the native object.
   context->SetAlignedPointerInEmbedderData(
-      ContextEmbedderIndex::kContextifyContext, nullptr);
+      ContextEmbedderIndex::kContextifyContext, nullptr, 0);
 
   // This must not be done before other context fields are initialized.
   ContextEmbedderTag::TagNodeContext(context);
@@ -695,11 +695,11 @@ void Environment::AssignToContext(Local<v8::Context> context,
 void Environment::UnassignFromContext(Local<v8::Context> context) {
   if (!context.IsEmpty()) {
     context->SetAlignedPointerInEmbedderData(ContextEmbedderIndex::kEnvironment,
-                                             nullptr);
+                                             nullptr, 0);
     context->SetAlignedPointerInEmbedderData(ContextEmbedderIndex::kRealm,
-                                             nullptr);
+                                             nullptr, 0);
     context->SetAlignedPointerInEmbedderData(
-        ContextEmbedderIndex::kContextifyContext, nullptr);
+        ContextEmbedderIndex::kContextifyContext, nullptr, 0);
   }
   UntrackContext(context);
 }
diff --git a/src/histogram.cc b/src/histogram.cc
index 836a51b0e5aa4b..e29b9fba04e469 100644
--- a/src/histogram.cc
+++ b/src/histogram.cc
@@ -136,7 +136,7 @@ HistogramBase::HistogramBase(
   MakeWeak();
   wrap->SetAlignedPointerInInternalField(
       HistogramImpl::InternalFields::kImplField,
-      static_cast<HistogramImpl*>(this));
+      static_cast<HistogramImpl*>(this), 0);
 }
 
 HistogramBase::HistogramBase(
@@ -148,7 +148,7 @@ HistogramBase::HistogramBase(
   MakeWeak();
   wrap->SetAlignedPointerInInternalField(
       HistogramImpl::InternalFields::kImplField,
-      static_cast<HistogramImpl*>(this));
+      static_cast<HistogramImpl*>(this), 0);
 }
 
 void HistogramBase::MemoryInfo(MemoryTracker* tracker) const {
@@ -362,7 +362,7 @@ IntervalHistogram::IntervalHistogram(
   MakeWeak();
   wrap->SetAlignedPointerInInternalField(
       HistogramImpl::InternalFields::kImplField,
-      static_cast<HistogramImpl*>(this));
+      static_cast<HistogramImpl*>(this), 0);
   uv_timer_init(env->event_loop(), &timer_);
 }
 
@@ -601,7 +601,7 @@ HistogramImpl* HistogramImpl::FromJSObject(Local<Value> value) {
   auto obj = value.As<Object>();
   DCHECK_GE(obj->InternalFieldCount(), HistogramImpl::kInternalFieldCount);
   return static_cast<HistogramImpl*>(
-      obj->GetAlignedPointerFromInternalField(HistogramImpl::kImplField));
+      obj->GetAlignedPointerFromInternalField(HistogramImpl::kImplField, 0));
 }
 
 std::unique_ptr<worker::TransferData>
diff --git a/src/js_udp_wrap.cc b/src/js_udp_wrap.cc
index 51e4f8c45ffd38..2cf2b097441872 100644
--- a/src/js_udp_wrap.cc
+++ b/src/js_udp_wrap.cc
@@ -56,7 +56,7 @@ JSUDPWrap::JSUDPWrap(Environment* env, Local<Object> obj)
   MakeWeak();
 
   obj->SetAlignedPointerInInternalField(
-      kUDPWrapBaseField, static_cast<UDPWrapBase*>(this));
+      kUDPWrapBaseField, static_cast<UDPWrapBase*>(this), 0);
 }
 
 int JSUDPWrap::RecvStart() {
diff --git a/src/node_context_data.h b/src/node_context_data.h
index d81c75daaae47b..dd6887c9fd6055 100644
--- a/src/node_context_data.h
+++ b/src/node_context_data.h
@@ -135,7 +135,7 @@ class ContextEmbedderTag {
     // context.
     context->SetAlignedPointerInEmbedderData(
         ContextEmbedderIndex::kContextTag,
-        ContextEmbedderTag::kNodeContextTagPtr);
+        ContextEmbedderTag::kNodeContextTagPtr, 0);
   }
 
   static inline bool IsNodeContext(v8::Local<v8::Context> context) {
@@ -147,7 +147,7 @@ class ContextEmbedderTag {
       return false;
     }
     if (context->GetAlignedPointerFromEmbedderData(
-            ContextEmbedderIndex::kContextTag) !=
+            ContextEmbedderIndex::kContextTag, 0) !=
         ContextEmbedderTag::kNodeContextTagPtr) [[unlikely]] {
       return false;
     }
diff --git a/src/node_contextify.cc b/src/node_contextify.cc
index 8dc96588f2cd28..ca4b8f70513b9a 100644
--- a/src/node_contextify.cc
+++ b/src/node_contextify.cc
@@ -163,9 +163,9 @@ ContextifyContext::ContextifyContext(Environment* env,
   // This should only be done after the initial initializations of the context
   // global object is finished.
   DCHECK_NULL(v8_context->GetAlignedPointerFromEmbedderData(
-      ContextEmbedderIndex::kContextifyContext));
+      ContextEmbedderIndex::kContextifyContext, 0));
   v8_context->SetAlignedPointerInEmbedderData(
-      ContextEmbedderIndex::kContextifyContext, this);
+      ContextEmbedderIndex::kContextifyContext, this, 0);
 }
 
 void ContextifyContext::InitializeGlobalTemplates(IsolateData* isolate_data) {
@@ -472,7 +472,7 @@ ContextifyContext* ContextifyContext::Get(Local<Object> object) {
   }
   return static_cast<ContextifyContext*>(
       context->GetAlignedPointerFromEmbedderData(
-          ContextEmbedderIndex::kContextifyContext));
+          ContextEmbedderIndex::kContextifyContext, 0));
 }
 
 bool ContextifyContext::IsStillInitializing(const ContextifyContext* ctx) {
diff --git a/src/node_object_wrap.h b/src/node_object_wrap.h
index cb13d84388bcc6..c2d5f80c1d073d 100644
--- a/src/node_object_wrap.h
+++ b/src/node_object_wrap.h
@@ -49,7 +49,8 @@ class ObjectWrap {
     assert(handle->InternalFieldCount() > 0);
     // Cast to ObjectWrap before casting to T.  A direct cast from void
     // to T won't work right when T has more than one base class.
-    void* ptr = handle->GetAlignedPointerFromInternalField(0);
+    void* ptr = handle->GetAlignedPointerFromInternalField(
+        0, v8::EmbedderDataTypeTag(0));
     ObjectWrap* wrap = static_cast<ObjectWrap*>(ptr);
     return static_cast<T*>(wrap);
   }
@@ -75,7 +76,7 @@ class ObjectWrap {
   inline void Wrap(v8::Local<v8::Object> handle) {
     assert(persistent().IsEmpty());
     assert(handle->InternalFieldCount() > 0);
-    handle->SetAlignedPointerInInternalField(0, this);
+    handle->SetAlignedPointerInInternalField(0, this, 0);
     persistent().Reset(v8::Isolate::GetCurrent(), handle);
     MakeWeak();
   }
diff --git a/src/node_process_methods.cc b/src/node_process_methods.cc
index 9b33f695b1003a..2b23424ccf3539 100644
--- a/src/node_process_methods.cc
+++ b/src/node_process_methods.cc
@@ -679,7 +679,7 @@ void BindingData::RegisterExternalReferences(
 BindingData* BindingData::FromV8Value(Local<Value> value) {
   Local<Object> v8_object = value.As<Object>();
   return static_cast<BindingData*>(
-      v8_object->GetAlignedPointerFromInternalField(BaseObject::kSlot));
+      v8_object->GetAlignedPointerFromInternalField(BaseObject::kSlot, 0));
 }
 
 void BindingData::MemoryInfo(MemoryTracker* tracker) const {
diff --git a/src/node_realm-inl.h b/src/node_realm-inl.h
index f162d1506c990a..11672b36a03e9b 100644
--- a/src/node_realm-inl.h
+++ b/src/node_realm-inl.h
@@ -20,8 +20,8 @@ inline Realm* Realm::GetCurrent(v8::Local<v8::Context> context) {
   if (!ContextEmbedderTag::IsNodeContext(context)) [[unlikely]] {
     return nullptr;
   }
-  return static_cast<Realm*>(
-      context->GetAlignedPointerFromEmbedderData(ContextEmbedderIndex::kRealm));
+  return static_cast<Realm*>(context->GetAlignedPointerFromEmbedderData(
+      ContextEmbedderIndex::kRealm, 0));
 }
 
 inline Realm* Realm::GetCurrent(
diff --git a/src/node_snapshotable.cc b/src/node_snapshotable.cc
index e34d24d51d5c09..5f8b7700a70b6a 100644
--- a/src/node_snapshotable.cc
+++ b/src/node_snapshotable.cc
@@ -1309,7 +1309,7 @@ StartupData SerializeNodeContextData(Local<Context> holder,
     case ContextEmbedderIndex::kContextifyContext:
     case ContextEmbedderIndex::kRealm:
     case ContextEmbedderIndex::kContextTag: {
-      void* data = holder->GetAlignedPointerFromEmbedderData(index);
+      void* data = holder->GetAlignedPointerFromEmbedderData(index, 0);
       per_process::Debug(
           DebugCategory::MKSNAPSHOT,
           "Serialize context data, index=%d, holder=%p, ptr=%p\n",
@@ -1400,7 +1400,7 @@ StartupData SerializeNodeContextInternalFields(Local<Object> holder,
   // For the moment we do not set any internal fields in ArrayBuffer
   // or ArrayBufferViews, so just return nullptr.
   if (holder->IsArrayBuffer() || holder->IsArrayBufferView()) {
-    CHECK_NULL(holder->GetAlignedPointerFromInternalField(index));
+    CHECK_NULL(holder->GetAlignedPointerFromInternalField(index, 0));
     return StartupData{nullptr, 0};
   }
 
@@ -1420,7 +1420,7 @@ StartupData SerializeNodeContextInternalFields(Local<Object> holder,
                      *holder);
 
   BaseObject* object_ptr = static_cast<BaseObject*>(
-      holder->GetAlignedPointerFromInternalField(BaseObject::kSlot));
+      holder->GetAlignedPointerFromInternalField(BaseObject::kSlot, 0));
   // If the native object is already set to null, ignore it.
   if (object_ptr == nullptr) {
     return StartupData{nullptr, 0};
diff --git a/src/stream_base-inl.h b/src/stream_base-inl.h
index 29a4c29f3d3822..b1881adbd82604 100644
--- a/src/stream_base-inl.h
+++ b/src/stream_base-inl.h
@@ -19,22 +19,22 @@ StreamReq::StreamReq(
 
 void StreamReq::AttachToObject(v8::Local<v8::Object> req_wrap_obj) {
   CHECK_EQ(req_wrap_obj->GetAlignedPointerFromInternalField(
-               StreamReq::kStreamReqField),
+               StreamReq::kStreamReqField, 0),
            nullptr);
   req_wrap_obj->SetAlignedPointerInInternalField(
-      StreamReq::kStreamReqField, this);
+      StreamReq::kStreamReqField, this, 0);
 }
 
 StreamReq* StreamReq::FromObject(v8::Local<v8::Object> req_wrap_obj) {
   return static_cast<StreamReq*>(
       req_wrap_obj->GetAlignedPointerFromInternalField(
-          StreamReq::kStreamReqField));
+          StreamReq::kStreamReqField, 0));
 }
 
 void StreamReq::Dispose() {
   BaseObjectPtr<AsyncWrap> destroy_me{GetAsyncWrap()};
   object()->SetAlignedPointerInInternalField(
-      StreamReq::kStreamReqField, nullptr);
+      StreamReq::kStreamReqField, nullptr, 0);
   destroy_me->Detach();
 }
 
@@ -119,17 +119,15 @@ SimpleWriteWrap<OtherBase>::SimpleWriteWrap(
 }
 
 void StreamBase::AttachToObject(v8::Local<v8::Object> obj) {
-  obj->SetAlignedPointerInInternalField(
-      StreamBase::kStreamBaseField, this);
+  obj->SetAlignedPointerInInternalField(StreamBase::kStreamBaseField, this, 0);
 }
 
 StreamBase* StreamBase::FromObject(v8::Local<v8::Object> obj) {
-  if (obj->GetAlignedPointerFromInternalField(StreamBase::kSlot) == nullptr)
+  if (obj->GetAlignedPointerFromInternalField(StreamBase::kSlot, 0) == nullptr)
     return nullptr;
 
   return static_cast<StreamBase*>(
-      obj->GetAlignedPointerFromInternalField(
-          StreamBase::kStreamBaseField));
+      obj->GetAlignedPointerFromInternalField(StreamBase::kStreamBaseField, 0));
 }
 
 WriteWrap* WriteWrap::FromObject(v8::Local<v8::Object> req_wrap_obj) {
@@ -162,8 +160,8 @@ void WriteWrap::SetBackingStore(std::unique_ptr<v8::BackingStore> bs) {
 void StreamReq::ResetObject(v8::Local<v8::Object> obj) {
   DCHECK_GT(obj->InternalFieldCount(), StreamReq::kStreamReqField);
 
-  obj->SetAlignedPointerInInternalField(StreamReq::kSlot, nullptr);
-  obj->SetAlignedPointerInInternalField(StreamReq::kStreamReqField, nullptr);
+  obj->SetAlignedPointerInInternalField(StreamReq::kSlot, nullptr, 0);
+  obj->SetAlignedPointerInInternalField(StreamReq::kStreamReqField, nullptr, 0);
 }
 
 }  // namespace node
diff --git a/src/udp_wrap.cc b/src/udp_wrap.cc
index 0821d07b5cde7c..11af4b58715b73 100644
--- a/src/udp_wrap.cc
+++ b/src/udp_wrap.cc
@@ -127,8 +127,8 @@ void UDPWrapBase::set_listener(UDPListener* listener) {
 
 UDPWrapBase* UDPWrapBase::FromObject(Local<Object> obj) {
   CHECK_GT(obj->InternalFieldCount(), UDPWrapBase::kUDPWrapBaseField);
-  return static_cast<UDPWrapBase*>(
-      obj->GetAlignedPointerFromInternalField(UDPWrapBase::kUDPWrapBaseField));
+  return static_cast<UDPWrapBase*>(obj->GetAlignedPointerFromInternalField(
+      UDPWrapBase::kUDPWrapBaseField, 0));
 }
 
 void UDPWrapBase::AddMethods(Environment* env, Local<FunctionTemplate> t) {
@@ -148,7 +148,7 @@ UDPWrap::UDPWrap(Environment* env, Local<Object> object)
                  reinterpret_cast<uv_handle_t*>(&handle_),
                  AsyncWrap::PROVIDER_UDPWRAP) {
   object->SetAlignedPointerInInternalField(
-      UDPWrapBase::kUDPWrapBaseField, static_cast<UDPWrapBase*>(this));
+      UDPWrapBase::kUDPWrapBaseField, static_cast<UDPWrapBase*>(this), 0);
 
   int r = uv_udp_init(env->event_loop(), &handle_);
   CHECK_EQ(r, 0);  // can't fail anyway