diff --git a/libs/ardour/session_transport.cc b/libs/ardour/session_transport.cc
index b82bd982db..38cb2b5018 100644
--- a/libs/ardour/session_transport.cc
+++ b/libs/ardour/session_transport.cc
@@ -30,7 +30,9 @@
 
 #include <cmath>
 #include <cerrno>
+#ifdef HAVE_UNISTD_H
 #include <unistd.h>
+#endif
 
 #include "pbd/atomic.h"
 #include "pbd/error.h"