diff --git a/libs/ardour/audio_unit.cc b/libs/ardour/audio_unit.cc
index ca36c729aa..428138ab54 100644
--- a/libs/ardour/audio_unit.cc
+++ b/libs/ardour/audio_unit.cc
@@ -455,6 +455,9 @@ AUPlugin::AUPlugin (const AUPlugin& other)
 
 {
 	init ();
+	for (int i = 0; i < descriptors.size(); ++i) {
+		set_parameter (i, other.get_parameter (i));
+	}
 }
 
 AUPlugin::~AUPlugin ()