diff --git a/modules/libcom/src/osi/os/vxWorks/osdFindSymbol.c b/modules/libcom/src/osi/os/vxWorks/osdFindSymbol.c
index 59bfc4f..b60cf0e 100644
--- a/modules/libcom/src/osi/os/vxWorks/osdFindSymbol.c
+++ b/modules/libcom/src/osi/os/vxWorks/osdFindSymbol.c
@@ -21,6 +21,7 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <loadLib.h>
+#include <ioLib.h>
 
 #include "dbmf.h"
 #include "epicsString.h"
diff --git a/modules/libcom/src/osi/os/vxWorks/osiUnistd.h b/modules/libcom/src/osi/os/vxWorks/osiUnistd.h
new file mode 100644
index 0000000..3f767ae
--- /dev/null
+++ b/modules/libcom/src/osi/os/vxWorks/osiUnistd.h
@@ -0,0 +1,21 @@
+/*************************************************************************\
+* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
+*     National Laboratory.
+* Copyright (c) 2002 The Regents of the University of California, as
+*     Operator of Los Alamos National Laboratory.
+* SPDX-License-Identifier: EPICS
+* EPICS Base is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+/*
+ *  Author Jeffrey O. Hill
+ *  johill@lanl.gov
+ *  505 665 1831
+ */
+
+#include <unistd.h>
+
+/* VxWorks has some functions in ioLib.h instead of unistd.h,
+   for example close() and read()
+ */
+#include <ioLib.h>