diff --git a/include/ArduinoJson/Internals/JsonNodeWrapper.h b/include/ArduinoJson/Internals/JsonNodeWrapper.h
index 4447afd2..45fe0aff 100644
--- a/include/ArduinoJson/Internals/JsonNodeWrapper.h
+++ b/include/ArduinoJson/Internals/JsonNodeWrapper.h
@@ -5,7 +5,7 @@ class JsonValue;
 
 class JsonNodeWrapper
 {
-    friend JsonValue;
+    friend class JsonValue;
 
 public:
     JsonNodeWrapper()
diff --git a/include/ArduinoJson/JsonContainer.h b/include/ArduinoJson/JsonContainer.h
index a5ff0689..31137c58 100644
--- a/include/ArduinoJson/JsonContainer.h
+++ b/include/ArduinoJson/JsonContainer.h
@@ -13,7 +13,7 @@ class JsonValue;
 class JsonContainer : public Printable, public JsonNodeWrapper
 {
   // friend JsonValue;
-    friend JsonArray;
+    friend class JsonArray;
 
 public:
 
diff --git a/include/ArduinoJson/StaticJsonBuffer.h b/include/ArduinoJson/StaticJsonBuffer.h
index c3e9ee64..8b85491f 100644
--- a/include/ArduinoJson/StaticJsonBuffer.h
+++ b/include/ArduinoJson/StaticJsonBuffer.h
@@ -6,7 +6,7 @@
 template<int CAPACITY>
 class StaticJsonBuffer : public JsonBuffer
 {
-    friend JsonObject;
+    friend class JsonObject;
 
 public: