diff --git a/src/Traffic/Schedule.cxx b/src/Traffic/Schedule.cxx
index ce6deedab..cc9a90e45 100644
--- a/src/Traffic/Schedule.cxx
+++ b/src/Traffic/Schedule.cxx
@@ -28,6 +28,7 @@
 
 #include <string>
 #include <vector>
+#include <algorithm>
 
 #include <plib/sg.h>
 
@@ -48,6 +49,7 @@
 #include "SchedFlight.hxx"
 #include "TrafficMgr.hxx"
 
+SG_USING_STD( sort );
 
 /******************************************************************************
  * the FGAISchedule class contains data members and code to maintain a