diff --git lib/src/h4toh5main.h lib/src/h4toh5main.h
index ab37713..12fb265 100644
--- lib/src/h4toh5main.h
+++ lib/src/h4toh5main.h
@@ -43,6 +43,8 @@ Author:  Kent Yang(myang6@hdfgroup.org)
 
 #endif
 
+#include <unistd.h>
+
 /* For windows support.*/
 #ifdef WIN32
 typedef unsigned int mode_t;
diff --git lib/src/h4toh5util.h lib/src/h4toh5util.h
index 999824c..d704a6e 100644
--- lib/src/h4toh5util.h
+++ lib/src/h4toh5util.h
@@ -47,6 +47,7 @@ Author:  Kent Yang(myang6@hdfgroup.org)
 #include "mfhdf.h"
 #include "H4TOH5Ipublic.h"
 #include "H4TOH5Iprivate.h"
+#include "H5DSpublic.h"
 #include "h4toh5.h"
 #include <string.h>
 
diff --git utils/h4toh5/h4toh5main.h utils/h4toh5/h4toh5main.h
index d7963bb..46e4b2a 100644
--- utils/h4toh5/h4toh5main.h
+++ utils/h4toh5/h4toh5main.h
@@ -46,6 +46,8 @@ Author:  Kent Yang(myang6@hdfgroup.org)
 #include "hdf5.h"
 #include <fcntl.h>
 #include <errno.h>
+#include <unistd.h>
+
 
 /* For windows support.*/
 #ifdef WIN32
diff --git utils/h5toh4/h5toh4.c utils/h5toh4/h5toh4.c
index cf94dea..a493b73 100644
--- utils/h5toh4/h5toh4.c
+++ utils/h5toh4/h5toh4.c
@@ -29,6 +29,7 @@
 #include <errno.h>
 #include <string.h>
 #include <fcntl.h>
+#include <unistd.h>
 
 #include <stdarg.h>
 #include <stdio.h>