diff --git a/CMakeLists.txt b/CMakeLists.txt
index b8991b8..bd3a0fc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -32,6 +32,9 @@ configure_file(
   "${PROJECT_SOURCE_DIR}/src/version.hpp.in"
   "${PROJECT_BINARY_DIR}/version.hpp")
 
+# Include <filesystem> or <experimental/filesystem>.
+configure_file(fs-compat.hpp.in fs-compat.hpp @ONLY)
+
 file(GLOB sources src/*.cpp)
 add_executable(${PROJECT_NAME} ${sources})
 target_include_directories(${PROJECT_NAME}
diff --git a/src/fs-compat.hpp.in b/src/fs-compat.hpp.in
new file mode 100644
index 0000000..ca15c69
--- /dev/null
+++ b/src/fs-compat.hpp.in
@@ -0,0 +1,2 @@
+#include <@CXX_FILESYSTEM_HEADER@>
+namespace fs = @CXX_FILESYSTEM_NAMESPACE@;
diff --git a/src/libravatarserv.hpp b/src/libravatarserv.hpp
index 7bcac62..41dcd1d 100644
--- a/src/libravatarserv.hpp
+++ b/src/libravatarserv.hpp
@@ -1,5 +1,5 @@
 /*  This file is part of libravatarserv.
- *  Copyright © 2018 tastytea <tastytea@tastytea.de>
+ *  Copyright © 2018, 2020 tastytea <tastytea@tastytea.de>
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -17,20 +17,12 @@
 #ifndef LIBRAVATARSERV_HPP
 #define LIBRAVATARSERV_HPP
 
-#if __cplusplus >= 201703L
-    #include <filesystem>
-#else
-    #include <experimental/filesystem>
-#endif
-#include <string>
-#include <map>
-#include <Magick++/Image.h>
+#include "fs-compat.hpp"
+
+#include <Magick++/Image.h>
+#include <map>
+#include <string>
 
-#if __cplusplus >= 201703L
-    namespace fs = std::filesystem;
-#else
-    namespace fs = std::experimental::filesystem;
-#endif
 using std::string;
 using std::uint16_t;
 using std::uint8_t;