diff --git a/src/Makefile.am b/src/Makefile.am
index 460b26a..92fc90c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,4 +1,4 @@
-include_HEADERS = jansson.h jansson.hpp jansson-impl.hpp
+include_HEADERS = jansson.h jansson.hpp jansson.ipp
 
 lib_LTLIBRARIES = libjansson.la
 libjansson_la_SOURCES = \
diff --git a/src/jansson.hpp b/src/jansson.hpp
index 41afd67..265b2b9 100644
--- a/src/jansson.hpp
+++ b/src/jansson.hpp
@@ -3,8 +3,8 @@
 // Jansson is free software; you can redistribute it and/or modify
 // it under the terms of the MIT license. See LICENSE for details.
 
-#if !defined(JANSSON_HPP)
-#define JANSSON_HPP 1
+#ifndef JANSSON_HPP
+#define JANSSON_HPP
 
 #include <string>
 #include <ostream>
@@ -296,8 +296,8 @@ inline std::ostream& operator<<(std::ostream& os, const json::Value& value);
 inline std::istream& operator>>(std::istream& is, json::Value& value);
 
 // include implementation code
-#define IN_JANSSON_HPP 1
-#include "jansson-impl.hpp"
+#define IN_JANSSON_HPP
+#include "jansson.ipp"
 #undef IN_JANSSON_HPP
 
 #endif // defined(JANSSON_HPP)
diff --git a/src/jansson-impl.hpp b/src/jansson.ipp
similarity index 99%
rename from src/jansson-impl.hpp
rename to src/jansson.ipp
index eb68fcd..a845e84 100644
--- a/src/jansson-impl.hpp
+++ b/src/jansson.ipp
@@ -3,8 +3,8 @@
 // Jansson is free software; you can redistribute it and/or modify
 // it under the terms of the MIT license. See LICENSE for details.
 
-#if !defined(IN_JANSSON_HPP)
-#error "jansson-impl.hpp may only by included from jansson.hpp"
+#ifndef IN_JANSSON_HPP
+#error "jansson.ipp may only be included from jansson.hpp"
 #endif
 
 namespace json {