diff --git a/include/inja/environment.hpp b/include/inja/environment.hpp
index 72b312b..791c3de 100644
--- a/include/inja/environment.hpp
+++ b/include/inja/environment.hpp
@@ -4,6 +4,7 @@
 #define INCLUDE_INJA_ENVIRONMENT_HPP_
 
 #include <fstream>
+#include <iostream>
 #include <memory>
 #include <sstream>
 #include <string>
diff --git a/include/inja/inja.hpp b/include/inja/inja.hpp
index 3075b51..fff245b 100644
--- a/include/inja/inja.hpp
+++ b/include/inja/inja.hpp
@@ -3,8 +3,6 @@
 #ifndef INCLUDE_INJA_INJA_HPP_
 #define INCLUDE_INJA_INJA_HPP_
 
-#include <iostream>
-
 #include <nlohmann/json.hpp>
 
 #include "environment.hpp"
diff --git a/single_include/inja/inja.hpp b/single_include/inja/inja.hpp
index 30277b1..0b7bb62 100644
--- a/single_include/inja/inja.hpp
+++ b/single_include/inja/inja.hpp
@@ -3,8 +3,6 @@
 #ifndef INCLUDE_INJA_INJA_HPP_
 #define INCLUDE_INJA_INJA_HPP_
 
-#include <iostream>
-
 #include <nlohmann/json.hpp>
 
 // #include "environment.hpp"
@@ -14,6 +12,7 @@
 #define INCLUDE_INJA_ENVIRONMENT_HPP_
 
 #include <fstream>
+#include <iostream>
 #include <memory>
 #include <sstream>
 #include <string>
diff --git a/test/benchmark.cpp b/test/benchmark.cpp
index 229146b..571a3ed 100644
--- a/test/benchmark.cpp
+++ b/test/benchmark.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2019 Pantor. All rights reserved.
+// Copyright (c) 2020 Pantor. All rights reserved.
 
 #include "hayai/hayai.hpp"
 #include <inja/inja.hpp>
diff --git a/test/test-files.cpp b/test/test-files.cpp
index 471a162..a999d90 100644
--- a/test/test-files.cpp
+++ b/test/test-files.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2019 Pantor. All rights reserved.
+// Copyright (c) 2020 Pantor. All rights reserved.
 
 #include "doctest/doctest.h"
 #include "inja/inja.hpp"
diff --git a/test/test-functions.cpp b/test/test-functions.cpp
index d233789..3d9d9cb 100644
--- a/test/test-functions.cpp
+++ b/test/test-functions.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2019 Pantor. All rights reserved.
+// Copyright (c) 2020 Pantor. All rights reserved.
 
 #include "doctest/doctest.h"
 #include "inja/inja.hpp"
diff --git a/test/test-renderer.cpp b/test/test-renderer.cpp
index 7345197..6837069 100644
--- a/test/test-renderer.cpp
+++ b/test/test-renderer.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2019 Pantor. All rights reserved.
+// Copyright (c) 2020 Pantor. All rights reserved.
 
 #include "doctest/doctest.h"
 #include "inja/inja.hpp"
diff --git a/test/test-units.cpp b/test/test-units.cpp
index 3a8c82b..f84197a 100644
--- a/test/test-units.cpp
+++ b/test/test-units.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2019 Pantor. All rights reserved.
+// Copyright (c) 2020 Pantor. All rights reserved.
 
 #include "doctest/doctest.h"
 #include "inja/inja.hpp"