--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -241,3 +241,4 @@ endif()
 install (FILES evhtp.h DESTINATION include)
 install (FILES htparse/htparse.h DESTINATION include)
 install (FILES evthr/evthr.h DESTINATION include)
+install (FILES oniguruma/onigposix.h DESTINATION include)