diff --git a/libs/ardour/session_state.cc b/libs/ardour/session_state.cc
index d3c73d99e4..7ccaca1a27 100644
--- a/libs/ardour/session_state.cc
+++ b/libs/ardour/session_state.cc
@@ -70,6 +70,7 @@
 #include "pbd/stacktrace.h"
 #include "pbd/convert.h"
 #include "pbd/clear_dir.h"
+#include "pbd/localtime_r.h"
 
 #include "ardour/amp.h"
 #include "ardour/audio_diskstream.h"