diff --git a/CHANGELOG.md b/CHANGELOG.md
index cb0dbbd0..dc7fb739 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,11 @@
 ArduinoJson: change log
 =======================
 
+HEAD
+----
+
+* Removed `String` duplication when one replaces a value in a `JsonObject` (PR #232 by @ulion)
+
 v5.1.0
 ------
 
diff --git a/include/ArduinoJson/JsonObject.ipp b/include/ArduinoJson/JsonObject.ipp
index 094656c5..8c28193a 100644
--- a/include/ArduinoJson/JsonObject.ipp
+++ b/include/ArduinoJson/JsonObject.ipp
@@ -55,8 +55,12 @@ inline void JsonObject::remove(JsonObjectKey key) {
 template <typename T>
 inline bool JsonObject::setNodeAt(JsonObjectKey key, T value) {
   node_type *node = getNodeAt(key.c_str());
-  if (!node) node = addNewNode();
-  return node && setNodeKey(node, key) && setNodeValue<T>(node, value);
+  if (!node) {
+    node = addNewNode();
+    if (!node || !setNodeKey(node, key))
+      return false;
+  }
+  return setNodeValue<T>(node, value);
 }
 
 inline bool JsonObject::setNodeKey(node_type *node, JsonObjectKey key) {
diff --git a/test/ArduinoString_Tests.cpp b/test/ArduinoString_Tests.cpp
index 1557dd5e..82da09e1 100644
--- a/test/ArduinoString_Tests.cpp
+++ b/test/ArduinoString_Tests.cpp
@@ -219,3 +219,27 @@ TEST_F(ArduinoStringTests, JsonObject_PrettyPrintTo) {
   object.prettyPrintTo(json);
   ASSERT_EQ(String("{\r\n  \"key\": \"value\"\r\n}"), json);
 }
+
+TEST_F(ArduinoStringTests, JsonBuffer_GrowWhenAddingNewKey) {
+  JsonObject &object = _jsonBuffer.createObject();
+  String key1("hello"), key2("world");
+
+  object[key1] = 1;
+  size_t sizeBefore = _jsonBuffer.size();
+  object[key2] = 2;
+  size_t sizeAfter = _jsonBuffer.size();
+
+  ASSERT_GT(sizeAfter - sizeBefore, key2.size());
+}
+
+TEST_F(ArduinoStringTests, JsonBuffer_DontGrowWhenReusingKey) {
+  JsonObject &object = _jsonBuffer.createObject();
+  String key("hello");
+
+  object[key] = 1;
+  size_t sizeBefore = _jsonBuffer.size();
+  object[key] = 2;
+  size_t sizeAfter = _jsonBuffer.size();
+
+  ASSERT_EQ(sizeBefore, sizeAfter);
+}