diff --git a/CMakeLists.txt b/CMakeLists.txt
index deca1ca..be84415 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,8 +28,8 @@ target_link_libraries(insane_dns BLT)
 
 if(THREADS_HAVE_PTHREAD_ARG)
     # annoying hack for asio on sandcastle
-    set_property(TARGET insane_dns PROPERTY COMPILE_OPTIONS "-pthread")
-    set_property(TARGET insane_dns PROPERTY INTERFACE_COMPILE_OPTIONS "-pthread")
+    set_property(TARGET insane_dns PROPERTY COMPILE_OPTIONS "-pthread -lstdc++fs")
+    set_property(TARGET insane_dns PROPERTY INTERFACE_COMPILE_OPTIONS "-pthread -lstdc++fs")
 endif()
 if(CMAKE_THREAD_LIBS_INIT)
     target_link_libraries(insane_dns "${CMAKE_THREAD_LIBS_INIT}")