diff --git a/gtk2_ardour/ardour_ui.cc b/gtk2_ardour/ardour_ui.cc
index 8ace0cee38..1a6e301ccc 100644
--- a/gtk2_ardour/ardour_ui.cc
+++ b/gtk2_ardour/ardour_ui.cc
@@ -33,6 +33,11 @@
 #include <sys/resource.h>
 #endif
 
+#ifdef __FreeBSD__
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#endif
+
 #include <stdint.h>
 #include <fcntl.h>
 #include <signal.h>