diff --git a/modules/src/system/access.c b/modules/src/system/access.c
index 20773c7d0..bde73af26 100644
--- a/modules/src/system/access.c
+++ b/modules/src/system/access.c
@@ -4,6 +4,7 @@
  */
 /* $Id$ */
 
+#include <unistd.h>
 #include "system.h"
 
 int
diff --git a/modules/src/system/close.c b/modules/src/system/close.c
index 03aa767df..32896d806 100644
--- a/modules/src/system/close.c
+++ b/modules/src/system/close.c
@@ -4,6 +4,7 @@
  */
 /* $Id$ */
 
+#include <unistd.h>
 #include "system.h"
 
 void
diff --git a/modules/src/system/create.c b/modules/src/system/create.c
index 21203c41b..27ca9daec 100644
--- a/modules/src/system/create.c
+++ b/modules/src/system/create.c
@@ -4,6 +4,7 @@
  */
 /* $Id$ */
 
+#include <fcntl.h>
 #include "system.h"
 
 extern File *_get_entry();
@@ -14,7 +15,7 @@ sys_create(filep, path, mode)
 	char *path;
 	int mode;
 {
-	register fd;
+	register int fd;
 	register File *fp;
 
 	if ((fp = _get_entry()) == (File *)0)
diff --git a/modules/src/system/open.c b/modules/src/system/open.c
index 1433cea9f..eed31dc13 100644
--- a/modules/src/system/open.c
+++ b/modules/src/system/open.c
@@ -4,6 +4,7 @@
  */
 /* $Id$ */
 
+#include <fcntl.h>
 #include <unistd.h>
 #include "system.h"
 
diff --git a/modules/src/system/read.c b/modules/src/system/read.c
index 850d68f35..f84c91de9 100644
--- a/modules/src/system/read.c
+++ b/modules/src/system/read.c
@@ -4,6 +4,7 @@
  */
 /* $Id$ */
 
+#include <unistd.h>
 #include "system.h"
 
 int