diff --git a/extras/conf_test/avr.cpp b/extras/conf_test/avr.cpp
index 4ffff564..71c08cce 100644
--- a/extras/conf_test/avr.cpp
+++ b/extras/conf_test/avr.cpp
@@ -10,8 +10,8 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(sizeof(ArduinoJson::detail::VariantSlot) == 6,
-              "sizeof(VariantSlot)");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 6,
+              "sizeof(VariantData)");
 
 void setup() {}
 void loop() {}
diff --git a/extras/conf_test/esp8266.cpp b/extras/conf_test/esp8266.cpp
index b2e6d06f..16139090 100644
--- a/extras/conf_test/esp8266.cpp
+++ b/extras/conf_test/esp8266.cpp
@@ -8,8 +8,8 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(sizeof(ArduinoJson::detail::VariantSlot) == 16,
-              "sizeof(VariantSlot)");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 16,
+              "sizeof(VariantData)");
 
 void setup() {}
 void loop() {}
diff --git a/extras/conf_test/linux32.cpp b/extras/conf_test/linux32.cpp
index ad0c97d5..1170a40e 100644
--- a/extras/conf_test/linux32.cpp
+++ b/extras/conf_test/linux32.cpp
@@ -8,7 +8,7 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(sizeof(ArduinoJson::detail::VariantSlot) == 12,
-              "sizeof(VariantSlot)");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 12,
+              "sizeof(VariantData)");
 
 int main() {}
diff --git a/extras/conf_test/linux64.cpp b/extras/conf_test/linux64.cpp
index e03e6cca..0b6fd16b 100644
--- a/extras/conf_test/linux64.cpp
+++ b/extras/conf_test/linux64.cpp
@@ -8,7 +8,7 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(sizeof(ArduinoJson::detail::VariantSlot) == 16,
-              "sizeof(VariantSlot)");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 16,
+              "sizeof(VariantData)");
 
 int main() {}
diff --git a/extras/conf_test/win32.cpp b/extras/conf_test/win32.cpp
index a9874efd..00620664 100644
--- a/extras/conf_test/win32.cpp
+++ b/extras/conf_test/win32.cpp
@@ -8,7 +8,7 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(sizeof(ArduinoJson::detail::VariantSlot) == 16,
-              "sizeof(VariantSlot)");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 16,
+              "sizeof(VariantData)");
 
 int main() {}
diff --git a/extras/conf_test/win64.cpp b/extras/conf_test/win64.cpp
index e03e6cca..0b6fd16b 100644
--- a/extras/conf_test/win64.cpp
+++ b/extras/conf_test/win64.cpp
@@ -8,7 +8,7 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(sizeof(ArduinoJson::detail::VariantSlot) == 16,
-              "sizeof(VariantSlot)");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 16,
+              "sizeof(VariantData)");
 
 int main() {}
diff --git a/extras/tests/ResourceManager/shrinkToFit.cpp b/extras/tests/ResourceManager/shrinkToFit.cpp
index 812e2005..ea2d6527 100644
--- a/extras/tests/ResourceManager/shrinkToFit.cpp
+++ b/extras/tests/ResourceManager/shrinkToFit.cpp
@@ -29,7 +29,7 @@ TEST_CASE("ResourceManager::shrinkToFit()") {
     REQUIRE(spyingAllocator.log() ==
             AllocatorLog{
                 Allocate(sizeofPool()),
-                Reallocate(sizeofPool(), sizeof(VariantSlot)),
+                Reallocate(sizeofPool(), sizeof(VariantData)),
             });
   }
 
@@ -50,7 +50,7 @@ TEST_CASE("ResourceManager::shrinkToFit()") {
 
     REQUIRE(spyingAllocator.log() ==
             AllocatorLog{
-                Reallocate(sizeofPool(), sizeof(VariantSlot)),
+                Reallocate(sizeofPool(), sizeof(VariantData)),
                 Reallocate(sizeofPoolList(ARDUINOJSON_INITIAL_POOL_COUNT * 2),
                            sizeofPoolList(ARDUINOJSON_INITIAL_POOL_COUNT + 1)),
             });
diff --git a/src/ArduinoJson/Array/ArrayImpl.hpp b/src/ArduinoJson/Array/ArrayImpl.hpp
index 2000567e..8e6af227 100644
--- a/src/ArduinoJson/Array/ArrayImpl.hpp
+++ b/src/ArduinoJson/Array/ArrayImpl.hpp
@@ -6,7 +6,7 @@
 
 #include <ArduinoJson/Array/ArrayData.hpp>
 #include <ArduinoJson/Variant/VariantCompare.hpp>
-#include <ArduinoJson/Variant/VariantSlot.hpp>
+#include <ArduinoJson/Variant/VariantData.hpp>
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
@@ -73,7 +73,7 @@ inline bool ArrayData::addValue(T&& value, ResourceManager* resources) {
 
 // Returns the size (in bytes) of an array with n elements.
 constexpr size_t sizeofArray(size_t n) {
-  return n * sizeof(VariantSlot);
+  return n * sizeof(VariantData);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE
diff --git a/src/ArduinoJson/Collection/CollectionData.hpp b/src/ArduinoJson/Collection/CollectionData.hpp
index aa0825bc..616ed18b 100644
--- a/src/ArduinoJson/Collection/CollectionData.hpp
+++ b/src/ArduinoJson/Collection/CollectionData.hpp
@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <ArduinoJson/Memory/ResourceManager.hpp>
 #include <ArduinoJson/Namespace.hpp>
 #include <ArduinoJson/Polyfills/assert.hpp>
 
@@ -12,7 +13,6 @@
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 class VariantData;
-union VariantSlot;
 
 class CollectionIterator {
   friend class CollectionData;
diff --git a/src/ArduinoJson/Memory/MemoryPool.hpp b/src/ArduinoJson/Memory/MemoryPool.hpp
index 23a95d85..35e623c8 100644
--- a/src/ArduinoJson/Memory/MemoryPool.hpp
+++ b/src/ArduinoJson/Memory/MemoryPool.hpp
@@ -10,7 +10,7 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-union VariantSlot;
+class VariantData;
 using SlotId = uint_t<ARDUINOJSON_SLOT_ID_SIZE * 8>;
 using SlotCount = SlotId;
 const SlotId NULL_SLOT = SlotId(-1);
@@ -18,7 +18,7 @@ const SlotId NULL_SLOT = SlotId(-1);
 class SlotWithId {
  public:
   SlotWithId() : slot_(nullptr), id_(NULL_SLOT) {}
-  SlotWithId(VariantSlot* slot, SlotId id) : slot_(slot), id_(id) {
+  SlotWithId(VariantData* slot, SlotId id) : slot_(slot), id_(id) {
     ARDUINOJSON_ASSERT((slot == nullptr) == (id == NULL_SLOT));
   }
 
@@ -30,17 +30,17 @@ class SlotWithId {
     return id_;
   }
 
-  VariantSlot* slot() const {
+  VariantData* slot() const {
     return slot_;
   }
 
-  VariantSlot* operator->() {
+  VariantData* operator->() {
     ARDUINOJSON_ASSERT(slot_ != nullptr);
     return slot_;
   }
 
  private:
-  VariantSlot* slot_;
+  VariantData* slot_;
   SlotId id_;
 };
 
@@ -50,7 +50,7 @@ class MemoryPool {
   void destroy(Allocator* allocator);
 
   SlotWithId allocSlot();
-  VariantSlot* getSlot(SlotId id) const;
+  VariantData* getSlot(SlotId id) const;
   void clear();
   void shrinkToFit(Allocator*);
   SlotCount usage() const;
@@ -61,7 +61,7 @@ class MemoryPool {
  private:
   SlotCount capacity_;
   SlotCount usage_;
-  VariantSlot* slots_;
+  VariantData* slots_;
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE
diff --git a/src/ArduinoJson/Memory/MemoryPoolImpl.hpp b/src/ArduinoJson/Memory/MemoryPoolImpl.hpp
index a8dbdf4c..d9ba7a58 100644
--- a/src/ArduinoJson/Memory/MemoryPoolImpl.hpp
+++ b/src/ArduinoJson/Memory/MemoryPoolImpl.hpp
@@ -5,14 +5,14 @@
 #pragma once
 
 #include <ArduinoJson/Memory/MemoryPool.hpp>
-#include <ArduinoJson/Variant/VariantSlot.hpp>
+#include <ArduinoJson/Variant/VariantData.hpp>
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 inline void MemoryPool::create(SlotCount cap, Allocator* allocator) {
   ARDUINOJSON_ASSERT(cap > 0);
   slots_ =
-      reinterpret_cast<VariantSlot*>(allocator->allocate(slotsToBytes(cap)));
+      reinterpret_cast<VariantData*>(allocator->allocate(slotsToBytes(cap)));
   capacity_ = slots_ ? cap : 0;
   usage_ = 0;
 }
@@ -26,7 +26,7 @@ inline void MemoryPool::destroy(Allocator* allocator) {
 }
 
 inline void MemoryPool::shrinkToFit(Allocator* allocator) {
-  auto newSlots = reinterpret_cast<VariantSlot*>(
+  auto newSlots = reinterpret_cast<VariantData*>(
       allocator->reallocate(slots_, slotsToBytes(usage_)));
   if (newSlots) {
     slots_ = newSlots;
@@ -44,7 +44,7 @@ inline SlotWithId MemoryPool::allocSlot() {
   return {slot, SlotId(index)};
 }
 
-inline VariantSlot* MemoryPool::getSlot(SlotId id) const {
+inline VariantData* MemoryPool::getSlot(SlotId id) const {
   ARDUINOJSON_ASSERT(id < usage_);
   return &slots_[id];
 }
@@ -58,11 +58,11 @@ inline void MemoryPool::clear() {
 }
 
 inline SlotCount MemoryPool::bytesToSlots(size_t n) {
-  return static_cast<SlotCount>(n / sizeof(VariantSlot));
+  return static_cast<SlotCount>(n / sizeof(VariantData));
 }
 
 inline size_t MemoryPool::slotsToBytes(SlotCount n) {
-  return n * sizeof(VariantSlot);
+  return n * sizeof(VariantData);
 }
 
 inline SlotWithId MemoryPoolList::allocFromFreeList() {
diff --git a/src/ArduinoJson/Memory/MemoryPoolList.hpp b/src/ArduinoJson/Memory/MemoryPoolList.hpp
index b2eae0da..96c1cc64 100644
--- a/src/ArduinoJson/Memory/MemoryPoolList.hpp
+++ b/src/ArduinoJson/Memory/MemoryPoolList.hpp
@@ -97,7 +97,7 @@ class MemoryPoolList {
 
   void freeSlot(SlotWithId slot);
 
-  VariantSlot* getSlot(SlotId id) const {
+  VariantData* getSlot(SlotId id) const {
     if (id == NULL_SLOT)
       return nullptr;
     auto poolIndex = SlotId(id / ARDUINOJSON_POOL_CAPACITY);
diff --git a/src/ArduinoJson/Memory/ResourceManager.hpp b/src/ArduinoJson/Memory/ResourceManager.hpp
index 28f97665..45e329cd 100644
--- a/src/ArduinoJson/Memory/ResourceManager.hpp
+++ b/src/ArduinoJson/Memory/ResourceManager.hpp
@@ -13,7 +13,6 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-union VariantSlot;
 class MemoryPool;
 class VariantData;
 class VariantWithId;
diff --git a/src/ArduinoJson/Memory/ResourceManagerImpl.hpp b/src/ArduinoJson/Memory/ResourceManagerImpl.hpp
index 2e112fa7..c1c949e6 100644
--- a/src/ArduinoJson/Memory/ResourceManagerImpl.hpp
+++ b/src/ArduinoJson/Memory/ResourceManagerImpl.hpp
@@ -7,7 +7,6 @@
 #include <ArduinoJson/Collection/CollectionData.hpp>
 #include <ArduinoJson/Memory/ResourceManager.hpp>
 #include <ArduinoJson/Variant/VariantData.hpp>
-#include <ArduinoJson/Variant/VariantSlot.hpp>
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
@@ -17,7 +16,7 @@ inline VariantWithId ResourceManager::allocVariant() {
     overflowed_ = true;
     return {};
   }
-  return {new (&p->variant) VariantData, p.id()};
+  return {new (p.slot()) VariantData, p.id()};
 }
 
 inline void ResourceManager::freeVariant(VariantWithId variant) {
diff --git a/src/ArduinoJson/Memory/StringPool.hpp b/src/ArduinoJson/Memory/StringPool.hpp
index d2f754c8..91851e80 100644
--- a/src/ArduinoJson/Memory/StringPool.hpp
+++ b/src/ArduinoJson/Memory/StringPool.hpp
@@ -12,7 +12,6 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-union VariantSlot;
 class MemoryPool;
 
 class StringPool {
diff --git a/src/ArduinoJson/Object/ObjectImpl.hpp b/src/ArduinoJson/Object/ObjectImpl.hpp
index 7830576e..b2280c4a 100644
--- a/src/ArduinoJson/Object/ObjectImpl.hpp
+++ b/src/ArduinoJson/Object/ObjectImpl.hpp
@@ -6,7 +6,7 @@
 
 #include <ArduinoJson/Object/ObjectData.hpp>
 #include <ArduinoJson/Variant/VariantCompare.hpp>
-#include <ArduinoJson/Variant/VariantSlot.hpp>
+#include <ArduinoJson/Variant/VariantData.hpp>
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
@@ -70,7 +70,7 @@ inline VariantData* ObjectData::addMember(TAdaptedString key,
 
 // Returns the size (in bytes) of an object with n members.
 constexpr size_t sizeofObject(size_t n) {
-  return 2 * n * sizeof(VariantSlot);
+  return 2 * n * sizeof(VariantData);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE
diff --git a/src/ArduinoJson/Variant/VariantData.hpp b/src/ArduinoJson/Variant/VariantData.hpp
index 87e37ecc..4a676cbe 100644
--- a/src/ArduinoJson/Variant/VariantData.hpp
+++ b/src/ArduinoJson/Variant/VariantData.hpp
@@ -538,7 +538,7 @@ class VariantWithId : public SlotWithId {
  public:
   VariantWithId() {}
   VariantWithId(VariantData* data, SlotId id)
-      : SlotWithId(reinterpret_cast<VariantSlot*>(data), id) {}
+      : SlotWithId(reinterpret_cast<VariantData*>(data), id) {}
 
   VariantData* data() {
     return reinterpret_cast<VariantData*>(slot());
diff --git a/src/ArduinoJson/Variant/VariantSlot.hpp b/src/ArduinoJson/Variant/VariantSlot.hpp
deleted file mode 100644
index efde6583..00000000
--- a/src/ArduinoJson/Variant/VariantSlot.hpp
+++ /dev/null
@@ -1,22 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright © 2014-2024, Benoit BLANCHON
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Memory/ResourceManager.hpp>
-#include <ArduinoJson/Polyfills/limits.hpp>
-#include <ArduinoJson/Polyfills/type_traits.hpp>
-#include <ArduinoJson/Variant/VariantData.hpp>
-
-ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
-
-struct StringNode;
-
-union VariantSlot {
-  VariantSlot() {}
-
-  VariantData variant;
-};
-
-ARDUINOJSON_END_PRIVATE_NAMESPACE