diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1735ddc8..5b0079d4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -45,4 +45,9 @@ add_subdirectory(src/callback)
 
 xo_export_cmake_config(${PROJECT_NAME} ${PROJECT_VERSION} ${PROJECT_NAME}Targets)
 
+# ----------------------------------------------------------------
+# install .hpp files
+
+xo_install_include_tree()
+
 # end CMakeLists.txt