diff --git a/motorApp/MotorSrc/motordrvCom.cc b/motorApp/MotorSrc/motordrvCom.cc
index 2c6155c8..b0323825 100644
--- a/motorApp/MotorSrc/motordrvCom.cc
+++ b/motorApp/MotorSrc/motordrvCom.cc
@@ -56,6 +56,7 @@ USAGE...        This file contains driver functions that are common
 #include        <callback.h>
 #include        <epicsThread.h>
 #include        <epicsExport.h>
+#include        <stdarg.h>
 
 #include        "motor.h"