- https://github.com/csound/csound/issues/1438

--- InOut/CMakeLists.txt.orig	2021-02-18 01:47:49 UTC
+++ InOut/CMakeLists.txt
@@ -15,7 +15,7 @@ option(USE_AUDIOUNIT "Build the CoreAudio AudioUnit I/
 option(USE_FLTK "Use FLTK for graphs and widget opcodes" ON)
 option(BUILD_VIRTUAL_KEYBOARD "Build Virtual MIDI keyboard" ON)
 
-list(APPEND CMAKE_REQUIRED_INCLUDES "/usr/local/include")
+list(APPEND CMAKE_REQUIRED_INCLUDES "${CMAKE_INSTALL_PREFIX}/include")
 
 # FIND LIBRARIES AND HEADERS