diff --git a/modules/libcom/src/osi/os/vxWorks/osdFindSymbol.c b/modules/libcom/src/osi/os/vxWorks/osdFindSymbol.c
index 624ea220c..f6a8e2514 100644
--- a/modules/libcom/src/osi/os/vxWorks/osdFindSymbol.c
+++ b/modules/libcom/src/osi/os/vxWorks/osdFindSymbol.c
@@ -20,6 +20,7 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <loadLib.h>
+#include <ioLib.h>
 
 #include "dbmf.h"
 #include "epicsString.h"