diff --git a/libs/ardour/enums.cc b/libs/ardour/enums.cc
index baf3a41df4..f3972f346c 100644
--- a/libs/ardour/enums.cc
+++ b/libs/ardour/enums.cc
@@ -343,7 +343,6 @@ setup_enum_writer ()
 	REGISTER_ENUM (AIFF);
 	REGISTER_ENUM (iXML);
 	REGISTER_ENUM (RF64);
-	REGISTER_ENUM (RF64);
 	REGISTER_ENUM (RF64_WAV);
 	REGISTER_ENUM (MBWF);
 	REGISTER (_HeaderFormat);