diff --git a/CHANGELOG.md b/CHANGELOG.md
index 36e00e082..a51776dc9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,11 @@
 ArduinoJson: change log
 =======================
 
+HEAD
+----
+
+* Added missing `#pragma once` (issue #310)
+
 v5.6.0
 ------
 
diff --git a/README.md b/README.md
index 22c8a03f1..cc95a1787 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,7 @@ Features
 * Portable (written in C++98)
 * Self-contained (no external dependency)
 * Small footprint
+* Header-only library
 * MIT License
 
 Works on
diff --git a/include/ArduinoJson.hpp b/include/ArduinoJson.hpp
index 7c38e6412..1573cb3be 100644
--- a/include/ArduinoJson.hpp
+++ b/include/ArduinoJson.hpp
@@ -5,6 +5,8 @@
 // https://github.com/bblanchon/ArduinoJson
 // If you like this project, please add a star!
 
+#pragma once
+
 #include "ArduinoJson/DynamicJsonBuffer.hpp"
 #include "ArduinoJson/JsonArray.hpp"
 #include "ArduinoJson/JsonObject.hpp"
diff --git a/include/ArduinoJson/Internals/JsonParser.ipp b/include/ArduinoJson/Internals/JsonParser.ipp
index 088670d35..efc102794 100644
--- a/include/ArduinoJson/Internals/JsonParser.ipp
+++ b/include/ArduinoJson/Internals/JsonParser.ipp
@@ -5,8 +5,10 @@
 // https://github.com/bblanchon/ArduinoJson
 // If you like this project, please add a star!
 
-#include "JsonParser.hpp"
+#pragma once
+
 #include "Comments.hpp"
+#include "JsonParser.hpp"
 
 inline bool ArduinoJson::Internals::JsonParser::skip(char charToSkip) {
   const char *ptr = skipSpacesAndComments(_readPtr);
diff --git a/include/ArduinoJson/JsonBuffer.ipp b/include/ArduinoJson/JsonBuffer.ipp
index 3099861b9..5f8294af1 100644
--- a/include/ArduinoJson/JsonBuffer.ipp
+++ b/include/ArduinoJson/JsonBuffer.ipp
@@ -5,6 +5,8 @@
 // https://github.com/bblanchon/ArduinoJson
 // If you like this project, please add a star!
 
+#pragma once
+
 #include "Internals/JsonParser.hpp"
 
 inline ArduinoJson::JsonArray &ArduinoJson::JsonBuffer::createArray() {