diff --git a/extras/conf_test/avr.cpp b/extras/conf_test/avr.cpp
index 769317a8..ae1ec6f1 100644
--- a/extras/conf_test/avr.cpp
+++ b/extras/conf_test/avr.cpp
@@ -12,7 +12,7 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 0, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(ArduinoJson::detail::ResourceManager::slotSize == 6, "slot size");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 6, "slot size");
 
 void setup() {}
 void loop() {}
diff --git a/extras/conf_test/esp8266.cpp b/extras/conf_test/esp8266.cpp
index b37bfd67..116ac7ac 100644
--- a/extras/conf_test/esp8266.cpp
+++ b/extras/conf_test/esp8266.cpp
@@ -10,7 +10,7 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(ArduinoJson::detail::ResourceManager::slotSize == 8, "slot size");
+static_assert(sizeof(VariantData) == 8, "slot size");
 
 void setup() {}
 void loop() {}
diff --git a/extras/conf_test/x64.cpp b/extras/conf_test/x64.cpp
index df6b044b..c221cd1d 100644
--- a/extras/conf_test/x64.cpp
+++ b/extras/conf_test/x64.cpp
@@ -10,7 +10,6 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(ArduinoJson::detail::ResourceManager::slotSize == 16,
-              "slot size");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 16, "slot size");
 
 int main() {}
diff --git a/extras/conf_test/x86.cpp b/extras/conf_test/x86.cpp
index 9dff8f17..8d7f4773 100644
--- a/extras/conf_test/x86.cpp
+++ b/extras/conf_test/x86.cpp
@@ -10,6 +10,6 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(ArduinoJson::detail::ResourceManager::slotSize == 8, "slot size");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 8, "slot size");
 
 int main() {}
diff --git a/src/ArduinoJson/Array/ArrayImpl.hpp b/src/ArduinoJson/Array/ArrayImpl.hpp
index b4fb1264..8db18959 100644
--- a/src/ArduinoJson/Array/ArrayImpl.hpp
+++ b/src/ArduinoJson/Array/ArrayImpl.hpp
@@ -73,7 +73,7 @@ inline bool ArrayData::addValue(const T& value, ResourceManager* resources) {
 
 // Returns the size (in bytes) of an array with n elements.
 constexpr size_t sizeofArray(size_t n) {
-  return n * ResourceManager::slotSize;
+  return n * sizeof(VariantData);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE
diff --git a/src/ArduinoJson/Memory/ResourceManager.hpp b/src/ArduinoJson/Memory/ResourceManager.hpp
index d566e3fa..4ea6b7b3 100644
--- a/src/ArduinoJson/Memory/ResourceManager.hpp
+++ b/src/ArduinoJson/Memory/ResourceManager.hpp
@@ -18,11 +18,7 @@ class VariantData;
 class VariantWithId;
 
 class ResourceManager {
-  using SlotData = VariantData;  // TODO: remove SlotData?
-
  public:
-  constexpr static size_t slotSize = sizeof(SlotData);
-
   ResourceManager(Allocator* allocator = DefaultAllocator::instance())
       : allocator_(allocator), overflowed_(false) {}
 
@@ -154,7 +150,7 @@ class ResourceManager {
   Allocator* allocator_;
   bool overflowed_;
   StringPool stringPool_;
-  MemoryPoolList<SlotData> variantPools_;
+  MemoryPoolList<VariantData> variantPools_;
   MemoryPoolList<const char*> staticStringsPools_;
 #if ARDUINOJSON_USE_8_BYTE_POOL
   MemoryPoolList<EightByteValue> eightBytePools_;
diff --git a/src/ArduinoJson/Memory/ResourceManagerImpl.hpp b/src/ArduinoJson/Memory/ResourceManagerImpl.hpp
index d046770b..c5cf7df2 100644
--- a/src/ArduinoJson/Memory/ResourceManagerImpl.hpp
+++ b/src/ArduinoJson/Memory/ResourceManagerImpl.hpp
@@ -21,9 +21,9 @@ inline Slot<VariantData> ResourceManager::allocVariant() {
   return slot;
 }
 
-inline void ResourceManager::freeVariant(Slot<VariantData> variant) {
-  variant->clear(this);
-  variantPools_.freeSlot({alias_cast<SlotData*>(variant.ptr()), variant.id()});
+inline void ResourceManager::freeVariant(Slot<VariantData> slot) {
+  slot->clear(this);
+  variantPools_.freeSlot(slot);
 }
 
 inline VariantData* ResourceManager::getVariant(SlotId id) const {
diff --git a/src/ArduinoJson/Object/ObjectImpl.hpp b/src/ArduinoJson/Object/ObjectImpl.hpp
index 34da0dab..ab9727c3 100644
--- a/src/ArduinoJson/Object/ObjectImpl.hpp
+++ b/src/ArduinoJson/Object/ObjectImpl.hpp
@@ -86,7 +86,7 @@ inline VariantData* ObjectData::addPair(VariantData** value,
 
 // Returns the size (in bytes) of an object with n members.
 constexpr size_t sizeofObject(size_t n) {
-  return 2 * n * ResourceManager::slotSize;
+  return 2 * n * sizeof(VariantData);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE