diff --git a/CHANGELOG.md b/CHANGELOG.md
index a6a9062f..03baeb51 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ HEAD
 * Restored the monotonic allocator because the code was getting too big
 * Reduced the memory usage
 * Reduced the code size
+* Renamed `JsonKey` to `JsonString`
 * Removed spurious files in the Particle library
 
 v6.6.0-beta (2018-11-13)
diff --git a/src/ArduinoJson.hpp b/src/ArduinoJson.hpp
index 70d1bd9f..e3c10ca7 100644
--- a/src/ArduinoJson.hpp
+++ b/src/ArduinoJson.hpp
@@ -38,9 +38,9 @@ typedef ARDUINOJSON_NAMESPACE::Pair JsonPair;
 typedef ARDUINOJSON_NAMESPACE::UInt JsonUInt;
 typedef ARDUINOJSON_NAMESPACE::VariantRef JsonVariant;
 typedef ARDUINOJSON_NAMESPACE::VariantConstRef JsonVariantConst;
+typedef ARDUINOJSON_NAMESPACE::String JsonString;
 using ARDUINOJSON_NAMESPACE::DeserializationError;
 using ARDUINOJSON_NAMESPACE::DynamicJsonDocument;
-using ARDUINOJSON_NAMESPACE::Key;
 using ARDUINOJSON_NAMESPACE::serialized;
 using ARDUINOJSON_NAMESPACE::StaticJsonDocument;
 }  // namespace ArduinoJson
diff --git a/src/ArduinoJson/Array/ArrayRef.hpp b/src/ArduinoJson/Array/ArrayRef.hpp
index 23059ffb..3f8a9d8f 100644
--- a/src/ArduinoJson/Array/ArrayRef.hpp
+++ b/src/ArduinoJson/Array/ArrayRef.hpp
@@ -101,7 +101,7 @@ class ArrayRef : public ArrayRefBase<CollectionData>, public Visitable {
   }
   //
   // bool add(TValue);
-  // TValue = char*, const char*, const FlashStringHelper*
+  // TValue = char*, const char*, const __FlashStringHelper*
   template <typename T>
   FORCE_INLINE bool add(T* value) const {
     return add().set(value);
diff --git a/src/ArduinoJson/Array/ArraySubscript.hpp b/src/ArduinoJson/Array/ArraySubscript.hpp
index 8fe71f78..2819dfc4 100644
--- a/src/ArduinoJson/Array/ArraySubscript.hpp
+++ b/src/ArduinoJson/Array/ArraySubscript.hpp
@@ -36,7 +36,7 @@ class ArraySubscript : public VariantOperators<ArraySubscript>,
   }
   //
   // operator=(TValue)
-  // TValue = char*, const char*, const FlashStringHelper*
+  // TValue = char*, const char*, const __FlashStringHelper*
   template <typename T>
   FORCE_INLINE ArraySubscript& operator=(T* src) {
     get_impl().set(src);
@@ -73,7 +73,7 @@ class ArraySubscript : public VariantOperators<ArraySubscript>,
   }
   //
   // bool set(TValue)
-  // TValue = char*, const char*, const FlashStringHelper*
+  // TValue = char*, const char*, const __FlashStringHelper*
   template <typename TValue>
   FORCE_INLINE bool set(TValue* value) const {
     return get_impl().set(value);
diff --git a/src/ArduinoJson/Collection/CollectionImpl.hpp b/src/ArduinoJson/Collection/CollectionImpl.hpp
index 45683a52..f4ed312a 100644
--- a/src/ArduinoJson/Collection/CollectionImpl.hpp
+++ b/src/ArduinoJson/Collection/CollectionImpl.hpp
@@ -53,9 +53,9 @@ inline bool CollectionData::copyFrom(const CollectionData& src,
     VariantData* var;
     if (s->key() != 0) {
       if (s->ownsKey())
-        var = add(ZeroTerminatedRamString(s->key()), pool);
+        var = add(RamStringWrapper(s->key()), pool);
       else
-        var = add(ZeroTerminatedRamStringConst(s->key()), pool);
+        var = add(ConstRamStringWrapper(s->key()), pool);
     } else {
       var = add(pool);
     }
@@ -69,7 +69,7 @@ inline bool CollectionData::equalsObject(const CollectionData& other) const {
   size_t count = 0;
   for (VariantSlot* slot = _head; slot; slot = slot->next()) {
     VariantData* v1 = slot->data();
-    VariantData* v2 = other.get(makeString(slot->key()));
+    VariantData* v2 = other.get(wrapString(slot->key()));
     if (!variantEquals(v1, v2)) return false;
     count++;
   }
diff --git a/src/ArduinoJson/Deserialization/CharPointerReader.hpp b/src/ArduinoJson/Deserialization/CharPointerReader.hpp
index e210c55a..63811086 100644
--- a/src/ArduinoJson/Deserialization/CharPointerReader.hpp
+++ b/src/ArduinoJson/Deserialization/CharPointerReader.hpp
@@ -51,7 +51,7 @@ inline SafeCharPointerReader makeReader(TChar* input, size_t n) {
 }
 
 #if ARDUINOJSON_ENABLE_ARDUINO_STRING
-inline SafeCharPointerReader makeReader(const String& input) {
+inline SafeCharPointerReader makeReader(const ::String& input) {
   return SafeCharPointerReader(input.c_str(), input.length());
 }
 #endif
diff --git a/src/ArduinoJson/Deserialization/deserialize.hpp b/src/ArduinoJson/Deserialization/deserialize.hpp
index bf686997..d2d5bdbd 100644
--- a/src/ArduinoJson/Deserialization/deserialize.hpp
+++ b/src/ArduinoJson/Deserialization/deserialize.hpp
@@ -35,7 +35,7 @@ deserialize(JsonDocument &doc, const TString &input) {
 }
 //
 // DeserializationError deserialize(JsonDocument& doc, TChar* input);
-// TChar* = char*, const char*, const FlashStringHelper*
+// TChar* = char*, const char*, const __FlashStringHelper*
 template <template <typename, typename> class TDeserializer, typename TChar>
 DeserializationError deserialize(JsonDocument &doc, TChar *input) {
   doc.clear();
@@ -47,7 +47,7 @@ DeserializationError deserialize(JsonDocument &doc, TChar *input) {
 //
 // DeserializationError deserialize(JsonDocument& doc, TChar* input, size_t
 // inputSize);
-// TChar* = char*, const char*, const FlashStringHelper*
+// TChar* = char*, const char*, const __FlashStringHelper*
 template <template <typename, typename> class TDeserializer, typename TChar>
 DeserializationError deserialize(JsonDocument &doc, TChar *input,
                                  size_t inputSize) {
diff --git a/src/ArduinoJson/Misc/SerializedValue.hpp b/src/ArduinoJson/Misc/SerializedValue.hpp
index 570b3dac..fa9de4d1 100644
--- a/src/ArduinoJson/Misc/SerializedValue.hpp
+++ b/src/ArduinoJson/Misc/SerializedValue.hpp
@@ -4,7 +4,7 @@
 
 #pragma once
 
-#include "../Strings/StringTypes.hpp"
+#include "../Strings/StringWrappers.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 
@@ -58,7 +58,7 @@ inline SerializedValue<T> serialized(T str) {
 
 template <typename TChar>
 inline SerializedValue<TChar*> serialized(TChar* p) {
-  return SerializedValue<TChar*>(p, makeString(p).size());
+  return SerializedValue<TChar*>(p, wrapString(p).size());
 }
 
 template <typename TChar>
diff --git a/src/ArduinoJson/Object/Key.hpp b/src/ArduinoJson/Object/Key.hpp
deleted file mode 100644
index d83c64bb..00000000
--- a/src/ArduinoJson/Object/Key.hpp
+++ /dev/null
@@ -1,33 +0,0 @@
-// ArduinoJson - arduinojson.org
-// Copyright Benoit Blanchon 2014-2018
-// MIT License
-
-#pragma once
-
-namespace ARDUINOJSON_NAMESPACE {
-
-class Key {
- public:
-  Key(const VariantSlot* slot) : _slot(slot) {}
-
-  operator const char*() const {
-    return c_str();
-  }
-
-  const char* c_str() const {
-    return _slot ? _slot->key() : 0;
-  }
-
-  bool isNull() const {
-    return _slot == 0 || _slot->key() == 0;
-  }
-
-  friend bool operator==(Key lhs, const char* rhs) {
-    if (lhs.isNull()) return rhs == 0;
-    return rhs ? !strcmp(lhs, rhs) : false;
-  }
-
- private:
-  const VariantSlot* _slot;
-};
-}  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Object/ObjectRef.hpp b/src/ArduinoJson/Object/ObjectRef.hpp
index 4d40788f..2a9edba9 100644
--- a/src/ArduinoJson/Object/ObjectRef.hpp
+++ b/src/ArduinoJson/Object/ObjectRef.hpp
@@ -28,14 +28,14 @@ class ObjectRefBase {
   // TKey = const std::string&, const String&
   template <typename TKey>
   FORCE_INLINE bool containsKey(const TKey& key) const {
-    return objectContainsKey(_data, makeString(key));
+    return objectContainsKey(_data, wrapString(key));
   }
   //
   // bool containsKey(TKey);
-  // TKey = char*, const char*, char[], const char[], const FlashStringHelper*
+  // TKey = char*, const char*, char[], const char[], const __FlashStringHelper*
   template <typename TKey>
   FORCE_INLINE bool containsKey(TKey* key) const {
-    return objectContainsKey(_data, makeString(key));
+    return objectContainsKey(_data, wrapString(key));
   }
 
   FORCE_INLINE bool isNull() const {
@@ -79,16 +79,16 @@ class ObjectConstRef : public ObjectRefBase<const CollectionData>,
   //          std::string, String, ArrayConstRef, ObjectConstRef
   template <typename TKey>
   FORCE_INLINE VariantConstRef get(const TKey& key) const {
-    return get_impl(makeString(key));
+    return get_impl(wrapString(key));
   }
   //
   // TValue get<TValue>(TKey) const;
-  // TKey = char*, const char*, const FlashStringHelper*
+  // TKey = char*, const char*, const __FlashStringHelper*
   // TValue = bool, char, long, int, short, float, double,
   //          std::string, String, ArrayConstRef, ObjectConstRef
   template <typename TKey>
   FORCE_INLINE VariantConstRef get(TKey* key) const {
-    return get_impl(makeString(key));
+    return get_impl(wrapString(key));
   }
 
   //
@@ -97,15 +97,15 @@ class ObjectConstRef : public ObjectRefBase<const CollectionData>,
   template <typename TKey>
   FORCE_INLINE typename enable_if<IsString<TKey>::value, VariantConstRef>::type
   operator[](const TKey& key) const {
-    return get_impl(makeString(key));
+    return get_impl(wrapString(key));
   }
   //
   // VariantConstRef operator[](TKey) const;
-  // TKey = const char*, const char[N], const FlashStringHelper*
+  // TKey = const char*, const char[N], const __FlashStringHelper*
   template <typename TKey>
   FORCE_INLINE typename enable_if<IsString<TKey*>::value, VariantConstRef>::type
   operator[](TKey* key) const {
-    return get_impl(makeString(key));
+    return get_impl(wrapString(key));
   }
 
   FORCE_INLINE bool operator==(ObjectConstRef rhs) const {
@@ -163,7 +163,7 @@ class ObjectRef : public ObjectRefBase<CollectionData>, public Visitable {
   template <typename TKey>
   FORCE_INLINE ArrayRef createNestedArray(const TKey& key) const;
   // ArrayRef createNestedArray(TKey);
-  // TKey = char*, const char*, char[], const char[], const FlashStringHelper*
+  // TKey = char*, const char*, char[], const char[], const __FlashStringHelper*
   template <typename TKey>
   FORCE_INLINE ArrayRef createNestedArray(TKey* key) const;
 
@@ -177,7 +177,7 @@ class ObjectRef : public ObjectRefBase<CollectionData>, public Visitable {
   }
   //
   // ObjectRef createNestedObject(TKey);
-  // TKey = char*, const char*, char[], const char[], const FlashStringHelper*
+  // TKey = char*, const char*, char[], const char[], const __FlashStringHelper*
   template <typename TKey>
   FORCE_INLINE ObjectRef createNestedObject(TKey* key) const {
     return set(key).template to<ObjectRef>();
@@ -191,16 +191,16 @@ class ObjectRef : public ObjectRefBase<CollectionData>, public Visitable {
   //          std::string, String, ArrayRef, ObjectRef
   template <typename TKey>
   FORCE_INLINE VariantRef get(const TKey& key) const {
-    return get_impl(makeString(key));
+    return get_impl(wrapString(key));
   }
   //
   // TValue get<TValue>(TKey) const;
-  // TKey = char*, const char*, const FlashStringHelper*
+  // TKey = char*, const char*, const __FlashStringHelper*
   // TValue = bool, char, long, int, short, float, double,
   //          std::string, String, ArrayRef, ObjectRef
   template <typename TKey>
   FORCE_INLINE VariantRef get(TKey* key) const {
-    return get_impl(makeString(key));
+    return get_impl(wrapString(key));
   }
 
   // Gets or sets the value associated with the specified key.
@@ -213,7 +213,8 @@ class ObjectRef : public ObjectRefBase<CollectionData>, public Visitable {
   }
   //
   // ObjectSubscript operator[](TKey)
-  // TKey = char*, const char*, char[], const char[N], const FlashStringHelper*
+  // TKey = char*, const char*, char[], const char[N], const
+  // __FlashStringHelper*
   template <typename TKey>
   FORCE_INLINE ObjectSubscript<TKey*> operator[](TKey* key) const {
     return ObjectSubscript<TKey*>(*this, key);
@@ -234,24 +235,24 @@ class ObjectRef : public ObjectRefBase<CollectionData>, public Visitable {
   // TKey = const std::string&, const String&
   template <typename TKey>
   FORCE_INLINE void remove(const TKey& key) const {
-    objectRemove(_data, makeString(key));
+    objectRemove(_data, wrapString(key));
   }
   //
   // void remove(TKey);
-  // TKey = char*, const char*, char[], const char[], const FlashStringHelper*
+  // TKey = char*, const char*, char[], const char[], const __FlashStringHelper*
   template <typename TKey>
   FORCE_INLINE void remove(TKey* key) const {
-    objectRemove(_data, makeString(key));
+    objectRemove(_data, wrapString(key));
   }
 
   template <typename TKey>
   FORCE_INLINE VariantRef set(TKey* key) const {
-    return set_impl(makeString(key));
+    return set_impl(wrapString(key));
   }
 
   template <typename TKey>
   FORCE_INLINE VariantRef set(const TKey& key) const {
-    return set_impl(makeString(key));
+    return set_impl(wrapString(key));
   }
 
  private:
diff --git a/src/ArduinoJson/Object/ObjectSubscript.hpp b/src/ArduinoJson/Object/ObjectSubscript.hpp
index f7361cb5..449dce6d 100644
--- a/src/ArduinoJson/Object/ObjectSubscript.hpp
+++ b/src/ArduinoJson/Object/ObjectSubscript.hpp
@@ -46,7 +46,7 @@ class ObjectSubscript : public VariantOperators<ObjectSubscript<TStringRef> >,
   }
   //
   // operator=(TValue);
-  // TValue = char*, const char*, const FlashStringHelper*
+  // TValue = char*, const char*, const __FlashStringHelper*
   template <typename TValue>
   FORCE_INLINE this_type &operator=(TValue *src) {
     set_impl().set(src);
@@ -85,7 +85,7 @@ class ObjectSubscript : public VariantOperators<ObjectSubscript<TStringRef> >,
   }
   //
   // bool set(TValue);
-  // TValue = char*, const char, const FlashStringHelper*
+  // TValue = char*, const char, const __FlashStringHelper*
   template <typename TValue>
   FORCE_INLINE bool set(const TValue *value) {
     return set_impl().set(value);
diff --git a/src/ArduinoJson/Object/Pair.hpp b/src/ArduinoJson/Object/Pair.hpp
index d13ea6b5..3baaf2db 100644
--- a/src/ArduinoJson/Object/Pair.hpp
+++ b/src/ArduinoJson/Object/Pair.hpp
@@ -4,20 +4,21 @@
 
 #pragma once
 
+#include "../Strings/String.hpp"
 #include "../Variant/VariantRef.hpp"
-#include "Key.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 // A key value pair for CollectionData.
 class Pair {
  public:
-  Pair(MemoryPool* pool, VariantSlot* slot) : _key(slot) {
+  Pair(MemoryPool* pool, VariantSlot* slot) {
     if (slot) {
+      _key = slot->key();
       _value = VariantRef(pool, slot->data());
     }
   }
 
-  Key key() const {
+  String key() const {
     return _key;
   }
 
@@ -26,19 +27,20 @@ class Pair {
   }
 
  private:
-  Key _key;
+  String _key;
   VariantRef _value;
 };
 
 class PairConst {
  public:
-  PairConst(const VariantSlot* slot) : _key(slot) {
+  PairConst(const VariantSlot* slot) {
     if (slot) {
+      _key = slot->key();
       _value = VariantConstRef(slot->data());
     }
   }
 
-  Key key() const {
+  String key() const {
     return _key;
   }
 
@@ -47,7 +49,7 @@ class PairConst {
   }
 
  private:
-  Key _key;
+  String _key;
   VariantConstRef _value;
 };
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Operators/VariantComparisons.hpp b/src/ArduinoJson/Operators/VariantComparisons.hpp
index 3a16e86b..e8474e98 100644
--- a/src/ArduinoJson/Operators/VariantComparisons.hpp
+++ b/src/ArduinoJson/Operators/VariantComparisons.hpp
@@ -21,28 +21,28 @@ class VariantComparisons {
   template <typename T>
   friend typename enable_if<IsString<T *>::value, bool>::type operator==(
       T *lhs, TVariant rhs) {
-    return makeString(lhs).equals(rhs.template as<const char *>());
+    return wrapString(lhs).equals(rhs.template as<const char *>());
   }
 
   // std::string == TVariant
   template <typename T>
   friend typename enable_if<IsString<T>::value, bool>::type operator==(
       const T &lhs, TVariant rhs) {
-    return makeString(lhs).equals(rhs.template as<const char *>());
+    return wrapString(lhs).equals(rhs.template as<const char *>());
   }
 
   // TVariant == const char*
   template <typename T>
   friend typename enable_if<IsString<T *>::value, bool>::type operator==(
       TVariant lhs, T *rhs) {
-    return makeString(rhs).equals(lhs.template as<const char *>());
+    return wrapString(rhs).equals(lhs.template as<const char *>());
   }
 
   // TVariant == std::string
   template <typename T>
   friend typename enable_if<IsString<T>::value, bool>::type operator==(
       TVariant lhs, const T &rhs) {
-    return makeString(rhs).equals(lhs.template as<const char *>());
+    return wrapString(rhs).equals(lhs.template as<const char *>());
   }
 
   // bool/int/float == TVariant
@@ -63,28 +63,28 @@ class VariantComparisons {
   template <typename T>
   friend typename enable_if<IsString<T *>::value, bool>::type operator!=(
       T *lhs, TVariant rhs) {
-    return !makeString(lhs).equals(rhs.template as<const char *>());
+    return !wrapString(lhs).equals(rhs.template as<const char *>());
   }
 
   // std::string != TVariant
   template <typename T>
   friend typename enable_if<IsString<T>::value, bool>::type operator!=(
       const T &lhs, TVariant rhs) {
-    return !makeString(lhs).equals(rhs.template as<const char *>());
+    return !wrapString(lhs).equals(rhs.template as<const char *>());
   }
 
   // TVariant != const char*
   template <typename T>
   friend typename enable_if<IsString<T *>::value, bool>::type operator!=(
       TVariant lhs, T *rhs) {
-    return !makeString(rhs).equals(lhs.template as<const char *>());
+    return !wrapString(rhs).equals(lhs.template as<const char *>());
   }
 
   // TVariant != std::string
   template <typename T>
   friend typename enable_if<IsString<T>::value, bool>::type operator!=(
       TVariant lhs, const T &rhs) {
-    return !makeString(rhs).equals(lhs.template as<const char *>());
+    return !wrapString(rhs).equals(lhs.template as<const char *>());
   }
 
   // bool/int/float != TVariant
diff --git a/src/ArduinoJson/Operators/VariantSubscripts.hpp b/src/ArduinoJson/Operators/VariantSubscripts.hpp
index 799fb1bc..664534b4 100644
--- a/src/ArduinoJson/Operators/VariantSubscripts.hpp
+++ b/src/ArduinoJson/Operators/VariantSubscripts.hpp
@@ -6,7 +6,7 @@
 
 #include "../Polyfills/attributes.hpp"
 #include "../Polyfills/type_traits.hpp"
-#include "../Strings/StringTypes.hpp"
+#include "../Strings/StringWrappers.hpp"
 #include "../Variant/VariantAs.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -37,7 +37,7 @@ class VariantSubscripts {
   operator[](const TString &key) const;
   //
   // ObjectSubscript operator[](TKey) const;
-  // TKey = const char*, const char[N], const FlashStringHelper*
+  // TKey = const char*, const char[N], const __FlashStringHelper*
   template <typename TString>
   FORCE_INLINE typename enable_if<IsString<TString *>::value,
                                   ObjectSubscript<TString *> >::type
diff --git a/src/ArduinoJson/Strings/ArduinoString.hpp b/src/ArduinoJson/Strings/ArduinoStringWrapper.hpp
similarity index 84%
rename from src/ArduinoJson/Strings/ArduinoString.hpp
rename to src/ArduinoJson/Strings/ArduinoStringWrapper.hpp
index fb3f1de8..20c87440 100644
--- a/src/ArduinoJson/Strings/ArduinoString.hpp
+++ b/src/ArduinoJson/Strings/ArduinoStringWrapper.hpp
@@ -8,9 +8,9 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
-class ArduinoString {
+class ArduinoStringWrapper {
  public:
-  ArduinoString(const ::String& str) : _str(&str) {}
+  ArduinoStringWrapper(const ::String& str) : _str(&str) {}
 
   char* save(MemoryPool* pool) const {
     if (isNull()) return NULL;
@@ -50,8 +50,8 @@ struct IsString< ::String> : true_type {};
 template <>
 struct IsString< ::StringSumHelper> : true_type {};
 
-inline ArduinoString makeString(const ::String& str) {
-  return ArduinoString(str);
+inline ArduinoStringWrapper wrapString(const ::String& str) {
+  return ArduinoStringWrapper(str);
 }
 
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Strings/ZeroTerminatedRamStringConst.hpp b/src/ArduinoJson/Strings/ConstRamStringWrapper.hpp
similarity index 77%
rename from src/ArduinoJson/Strings/ZeroTerminatedRamStringConst.hpp
rename to src/ArduinoJson/Strings/ConstRamStringWrapper.hpp
index c155566d..db329f4f 100644
--- a/src/ArduinoJson/Strings/ZeroTerminatedRamStringConst.hpp
+++ b/src/ArduinoJson/Strings/ConstRamStringWrapper.hpp
@@ -9,9 +9,9 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
-class ZeroTerminatedRamStringConst {
+class ConstRamStringWrapper {
  public:
-  ZeroTerminatedRamStringConst(const char* str = 0) : _str(str) {}
+  ConstRamStringWrapper(const char* str = 0) : _str(str) {}
 
   bool equals(const char* expected) const {
     const char* actual = _str;
@@ -40,8 +40,8 @@ class ZeroTerminatedRamStringConst {
   const char* _str;
 };
 
-inline ZeroTerminatedRamStringConst makeString(const char* str) {
-  return ZeroTerminatedRamStringConst(str);
+inline ConstRamStringWrapper wrapString(const char* str) {
+  return ConstRamStringWrapper(str);
 }
 
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Strings/ZeroTerminatedFlashString.hpp b/src/ArduinoJson/Strings/FlashStringWrapper.hpp
similarity index 79%
rename from src/ArduinoJson/Strings/ZeroTerminatedFlashString.hpp
rename to src/ArduinoJson/Strings/FlashStringWrapper.hpp
index cf3f22ab..12afe1a5 100644
--- a/src/ArduinoJson/Strings/ZeroTerminatedFlashString.hpp
+++ b/src/ArduinoJson/Strings/FlashStringWrapper.hpp
@@ -6,9 +6,9 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
-class ZeroTerminatedFlashString {
+class FlashStringWrapper {
  public:
-  ZeroTerminatedFlashString(const __FlashStringHelper* str) : _str(str) {}
+  FlashStringWrapper(const __FlashStringHelper* str) : _str(str) {}
 
   bool equals(const char* expected) const {
     const char* actual = reinterpret_cast<const char*>(_str);
@@ -36,8 +36,8 @@ class ZeroTerminatedFlashString {
   const __FlashStringHelper* _str;
 };
 
-inline ZeroTerminatedFlashString makeString(const __FlashStringHelper* str) {
-  return ZeroTerminatedFlashString(str);
+inline FlashStringWrapper wrapString(const __FlashStringHelper* str) {
+  return FlashStringWrapper(str);
 }
 
 template <>
diff --git a/src/ArduinoJson/Strings/ZeroTerminatedRamString.hpp b/src/ArduinoJson/Strings/RamStringWrapper.hpp
similarity index 58%
rename from src/ArduinoJson/Strings/ZeroTerminatedRamString.hpp
rename to src/ArduinoJson/Strings/RamStringWrapper.hpp
index db4384fd..d647104e 100644
--- a/src/ArduinoJson/Strings/ZeroTerminatedRamString.hpp
+++ b/src/ArduinoJson/Strings/RamStringWrapper.hpp
@@ -4,14 +4,13 @@
 
 #pragma once
 
-#include "ZeroTerminatedRamStringConst.hpp"
+#include "ConstRamStringWrapper.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
 
-class ZeroTerminatedRamString : public ZeroTerminatedRamStringConst {
+class RamStringWrapper : public ConstRamStringWrapper {
  public:
-  ZeroTerminatedRamString(const char* str)
-      : ZeroTerminatedRamStringConst(str) {}
+  RamStringWrapper(const char* str) : ConstRamStringWrapper(str) {}
 
   char* save(MemoryPool* pool) const {
     if (!_str) return NULL;
@@ -23,12 +22,12 @@ class ZeroTerminatedRamString : public ZeroTerminatedRamStringConst {
 };
 
 template <typename TChar>
-inline ZeroTerminatedRamString makeString(const TChar* str) {
-  return ZeroTerminatedRamString(reinterpret_cast<const char*>(str));
+inline RamStringWrapper wrapString(const TChar* str) {
+  return RamStringWrapper(reinterpret_cast<const char*>(str));
 }
 
-inline ZeroTerminatedRamString makeString(char* str) {
-  return ZeroTerminatedRamString(str);
+inline RamStringWrapper wrapString(char* str) {
+  return RamStringWrapper(str);
 }
 
 template <typename TChar>
diff --git a/src/ArduinoJson/Strings/FixedSizeFlashString.hpp b/src/ArduinoJson/Strings/SizedFlashStringWrapper.hpp
similarity index 75%
rename from src/ArduinoJson/Strings/FixedSizeFlashString.hpp
rename to src/ArduinoJson/Strings/SizedFlashStringWrapper.hpp
index afa76fc5..6cce023c 100644
--- a/src/ArduinoJson/Strings/FixedSizeFlashString.hpp
+++ b/src/ArduinoJson/Strings/SizedFlashStringWrapper.hpp
@@ -6,9 +6,9 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
-class FixedSizeFlashString {
+class SizedFlashStringWrapper {
  public:
-  FixedSizeFlashString(const __FlashStringHelper* str, size_t sz)
+  SizedFlashStringWrapper(const __FlashStringHelper* str, size_t sz)
       : _str(str), _size(sz) {}
 
   bool equals(const char* expected) const {
@@ -37,8 +37,8 @@ class FixedSizeFlashString {
   size_t _size;
 };
 
-inline FixedSizeFlashString makeString(const __FlashStringHelper* str,
-                                       size_t sz) {
-  return FixedSizeFlashString(str, sz);
+inline SizedFlashStringWrapper wrapString(const __FlashStringHelper* str,
+                                          size_t sz) {
+  return SizedFlashStringWrapper(str, sz);
 }
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Strings/FixedSizeRamString.hpp b/src/ArduinoJson/Strings/SizedRamStringWrapper.hpp
similarity index 76%
rename from src/ArduinoJson/Strings/FixedSizeRamString.hpp
rename to src/ArduinoJson/Strings/SizedRamStringWrapper.hpp
index 00da6503..95ce7ab8 100644
--- a/src/ArduinoJson/Strings/FixedSizeRamString.hpp
+++ b/src/ArduinoJson/Strings/SizedRamStringWrapper.hpp
@@ -8,9 +8,9 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
-class FixedSizeRamString {
+class SizedRamStringWrapper {
  public:
-  FixedSizeRamString(const char* str, size_t n) : _str(str), _size(n) {}
+  SizedRamStringWrapper(const char* str, size_t n) : _str(str), _size(n) {}
 
   bool equals(const char* expected) const {
     const char* actual = reinterpret_cast<const char*>(_str);
@@ -39,8 +39,8 @@ class FixedSizeRamString {
 };
 
 template <typename TChar>
-inline FixedSizeRamString makeString(const TChar* str, size_t size) {
-  return FixedSizeRamString(reinterpret_cast<const char*>(str), size);
+inline SizedRamStringWrapper wrapString(const TChar* str, size_t size) {
+  return SizedRamStringWrapper(reinterpret_cast<const char*>(str), size);
 }
 
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Strings/StlString.hpp b/src/ArduinoJson/Strings/StlStringWrapper.hpp
similarity index 81%
rename from src/ArduinoJson/Strings/StlString.hpp
rename to src/ArduinoJson/Strings/StlStringWrapper.hpp
index 12457ec3..813d1ee5 100644
--- a/src/ArduinoJson/Strings/StlString.hpp
+++ b/src/ArduinoJson/Strings/StlStringWrapper.hpp
@@ -8,9 +8,9 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
-class StlString {
+class StlStringWrapper {
  public:
-  StlString(const std::string& str) : _str(&str) {}
+  StlStringWrapper(const std::string& str) : _str(&str) {}
 
   char* save(MemoryPool* pool) const {
     size_t n = _str->length() + 1;
@@ -43,8 +43,8 @@ class StlString {
 template <>
 struct IsString<std::string> : true_type {};
 
-inline StlString makeString(const std::string& str) {
-  return StlString(str);
+inline StlStringWrapper wrapString(const std::string& str) {
+  return StlStringWrapper(str);
 }
 
 }  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Strings/String.hpp b/src/ArduinoJson/Strings/String.hpp
new file mode 100644
index 00000000..f9463a4b
--- /dev/null
+++ b/src/ArduinoJson/Strings/String.hpp
@@ -0,0 +1,32 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#pragma once
+
+namespace ARDUINOJSON_NAMESPACE {
+
+class String {
+ public:
+  String() : _data(0) {}
+  String(const char* slot) : _data(slot) {}
+
+  const char* c_str() const {
+    return _data;
+  }
+
+  bool isNull() const {
+    return !_data;
+  }
+
+  friend bool operator==(String lhs, String rhs) {
+    if (lhs._data == rhs._data) return true;
+    if (!lhs._data) return false;
+    if (!rhs._data) return false;
+    return strcmp(lhs._data, rhs._data) == 0;
+  }
+
+ private:
+  const char* _data;
+};
+}  // namespace ARDUINOJSON_NAMESPACE
diff --git a/src/ArduinoJson/Strings/StringTypes.hpp b/src/ArduinoJson/Strings/StringWrappers.hpp
similarity index 69%
rename from src/ArduinoJson/Strings/StringTypes.hpp
rename to src/ArduinoJson/Strings/StringWrappers.hpp
index 82481180..f9539469 100644
--- a/src/ArduinoJson/Strings/StringTypes.hpp
+++ b/src/ArduinoJson/Strings/StringWrappers.hpp
@@ -18,19 +18,19 @@ template <typename T>
 struct IsString<T&> : IsString<T> {};
 }  // namespace ARDUINOJSON_NAMESPACE
 
-#include "FixedSizeRamString.hpp"
-#include "ZeroTerminatedRamString.hpp"
-#include "ZeroTerminatedRamStringConst.hpp"
+#include "ConstRamStringWrapper.hpp"
+#include "RamStringWrapper.hpp"
+#include "SizedRamStringWrapper.hpp"
 
 #if ARDUINOJSON_ENABLE_STD_STRING
-#include "StlString.hpp"
+#include "StlStringWrapper.hpp"
 #endif
 
 #if ARDUINOJSON_ENABLE_ARDUINO_STRING
-#include "ArduinoString.hpp"
+#include "ArduinoStringWrapper.hpp"
 #endif
 
 #if ARDUINOJSON_ENABLE_PROGMEM
-#include "FixedSizeFlashString.hpp"
-#include "ZeroTerminatedFlashString.hpp"
+#include "FlashStringWrapper.hpp"
+#include "SizedFlashStringWrapper.hpp"
 #endif
diff --git a/src/ArduinoJson/Variant/SlotFunctions.hpp b/src/ArduinoJson/Variant/SlotFunctions.hpp
index 5e86b720..1b67d954 100644
--- a/src/ArduinoJson/Variant/SlotFunctions.hpp
+++ b/src/ArduinoJson/Variant/SlotFunctions.hpp
@@ -6,7 +6,7 @@
 
 #include "../Memory/MemoryPool.hpp"
 #include "../Polyfills/assert.hpp"
-#include "../Strings/StringTypes.hpp"
+#include "../Strings/StringWrappers.hpp"
 #include "VariantData.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -20,7 +20,7 @@ inline bool slotSetKey(VariantSlot* var, TKey key, MemoryPool* pool) {
   return true;
 }
 
-inline bool slotSetKey(VariantSlot* var, ZeroTerminatedRamStringConst key,
+inline bool slotSetKey(VariantSlot* var, ConstRamStringWrapper key,
                        MemoryPool*) {
   if (!var) return false;
   var->setLinkedKey(key.c_str());
diff --git a/src/ArduinoJson/Variant/VariantData.hpp b/src/ArduinoJson/Variant/VariantData.hpp
index 969dc937..69361a8f 100644
--- a/src/ArduinoJson/Variant/VariantData.hpp
+++ b/src/ArduinoJson/Variant/VariantData.hpp
@@ -95,8 +95,7 @@ class VariantData {
       case VALUE_IS_OBJECT:
         return toObject().copyFrom(src._content.asCollection, pool);
       case VALUE_IS_OWNED_STRING:
-        return setOwnedString(ZeroTerminatedRamString(src._content.asString),
-                              pool);
+        return setOwnedString(RamStringWrapper(src._content.asString), pool);
       case VALUE_IS_OWNED_RAW:
         return setOwnedRaw(
             serialized(src._content.asRaw.data, src._content.asRaw.size), pool);
@@ -190,7 +189,7 @@ class VariantData {
 
   template <typename T>
   bool setOwnedRaw(SerializedValue<T> value, MemoryPool *pool) {
-    char *dup = makeString(value.data(), value.size()).save(pool);
+    char *dup = wrapString(value.data(), value.size()).save(pool);
     if (dup) {
       setType(VALUE_IS_OWNED_RAW);
       _content.asRaw.data = dup;
diff --git a/src/ArduinoJson/Variant/VariantRef.hpp b/src/ArduinoJson/Variant/VariantRef.hpp
index 01ba5dff..c804e68a 100644
--- a/src/ArduinoJson/Variant/VariantRef.hpp
+++ b/src/ArduinoJson/Variant/VariantRef.hpp
@@ -183,7 +183,7 @@ class VariantRef : public VariantRefBase<VariantData>,
   FORCE_INLINE bool set(
       const T &value,
       typename enable_if<IsString<T>::value>::type * = 0) const {
-    return variantSetOwnedString(_data, makeString(value), _pool);
+    return variantSetOwnedString(_data, wrapString(value), _pool);
   }
 
   // set(char*)
@@ -191,7 +191,7 @@ class VariantRef : public VariantRefBase<VariantData>,
   template <typename T>
   FORCE_INLINE bool set(
       T *value, typename enable_if<IsString<T *>::value>::type * = 0) const {
-    return variantSetOwnedString(_data, makeString(value), _pool);
+    return variantSetOwnedString(_data, wrapString(value), _pool);
   }
 
   // set(const char*);
@@ -304,17 +304,17 @@ class VariantConstRef : public VariantRefBase<const VariantData>,
   FORCE_INLINE
       typename enable_if<IsString<TString>::value, VariantConstRef>::type
       operator[](const TString &key) const {
-    return VariantConstRef(objectGet(variantAsObject(_data), makeString(key)));
+    return VariantConstRef(objectGet(variantAsObject(_data), wrapString(key)));
   }
   //
   // VariantConstRef operator[](TKey);
-  // TKey = const char*, const char[N], const FlashStringHelper*
+  // TKey = const char*, const char[N], const __FlashStringHelper*
   template <typename TString>
   FORCE_INLINE
       typename enable_if<IsString<TString *>::value, VariantConstRef>::type
       operator[](TString *key) const {
     const CollectionData *obj = variantAsObject(_data);
-    return VariantConstRef(obj ? obj->get(makeString(key)) : 0);
+    return VariantConstRef(obj ? obj->get(wrapString(key)) : 0);
   }
 };
 }  // namespace ARDUINOJSON_NAMESPACE