diff --git a/libs/ardour/luabindings.cc b/libs/ardour/luabindings.cc
index e2ba1aa81c..33283c5c07 100644
--- a/libs/ardour/luabindings.cc
+++ b/libs/ardour/luabindings.cc
@@ -195,6 +195,7 @@ CLASSKEYS(ARDOUR::PortManager);
 CLASSKEYS(ARDOUR::AudioEngine);
 CLASSKEYS(void);
 CLASSKEYS(float);
+CLASSKEYS(unsigned char);
 
 #endif // end windows special case