diff --git a/vcv/src/mapping/midi_modules.cc b/vcv/src/mapping/midi_modules.cc
index f630fcf61..0f1e2b3e0 100644
--- a/vcv/src/mapping/midi_modules.cc
+++ b/vcv/src/mapping/midi_modules.cc
@@ -2,6 +2,7 @@
 #include "mapping/JackMap.hh"
 #include "mapping/module_directory.hh"
 #include "patch/midi_def.hh"
+#include <optional>
 #include <rack.hpp>
 
 namespace MetaModule::MIDI