diff --git a/CMakeLists.txt b/CMakeLists.txt
index b31e489..6199ac9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -137,10 +137,6 @@ SET(LIBRARY_HEADERS
 	SDL2pp/Window.hh
 )
 
-SET(LIBRARY_EXTERNAL_HEADERS
-	SDL2pp/external/libcpp_optional.hh
-)
-
 # optional sources
 IF(SDL2PP_WITH_TTF)
 	SET(LIBRARY_SOURCES
@@ -259,7 +255,6 @@ IF(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
 		${PROJECT_BINARY_DIR}/SDL2pp/Export.hh
 		DESTINATION include/SDL2pp
 	)
-	INSTALL(FILES ${LIBRARY_EXTERNAL_HEADERS} DESTINATION include/SDL2pp/external)
 	INSTALL(TARGETS SDL2pp
 		RUNTIME DESTINATION bin
 		LIBRARY DESTINATION lib