diff --git a/libs/ardour/ardour/luaproc.h b/libs/ardour/ardour/luaproc.h
index dcb5ec13cc..2102389c75 100644
--- a/libs/ardour/ardour/luaproc.h
+++ b/libs/ardour/ardour/luaproc.h
@@ -30,6 +30,7 @@
 #include <vector>
 #include <string>
 
+#define USE_TLSF
 #ifdef USE_TLSF
 #  include "pbd/tlsf.h"
 #else