diff --git a/README b/README
index 11421ac..6313d5d 100644
--- a/README
+++ b/README
@@ -114,9 +114,9 @@ embedded devices. Most of them are proprietary, with their own users. Some of
 them are structurally too simplistic, and lack modern features such as paging.
 There ones that are well established, but Codezero will contrast them by
 providing an alternative that will follow the open source development principles
-more closely. Many embedded software projects still use older development
-methods and the right open source methodology would prove favorable in the
-fast-paced nature of embedded software development.
+more closely. Many embedded software projects still use older or closed
+development methods and the right open source methodology would prove favorable
+in the fast-paced nature of embedded software development.
 
 Finally, POSIX compliance is only a step, or a temporary aim for the Codezero
 microkernel. It is not limited to the goal of just complying with POSIX, which
diff --git a/tasks/libposix/README b/tasks/libposix/README
index fe1d815..8822688 100644
--- a/tasks/libposix/README
+++ b/tasks/libposix/README
@@ -16,15 +16,28 @@ shmdt
 mmap
 munmap
 read
+readdir
 write
 lseek
 open
 close
 creat
+mkdir
+mknod
+link
 unlink
 fork
 execve
 getpid
+wait
+kill
+
+Others:
+pipe
+mount
+unmount
+swapon
+
 
 New ones will be added as needed.
 
diff --git a/tasks/mm0/src/file.c b/tasks/mm0/src/file.c
index 638f680..1563ead 100644
--- a/tasks/mm0/src/file.c
+++ b/tasks/mm0/src/file.c
@@ -412,6 +412,11 @@ int sys_write(l4id_t sender, int fd, void *buf, int count)
 
 	BUG_ON(!(t = find_task(sender)));
 
+	if ((err = check_access(t, buf, count)) < 0) {
+		l4_ipc_return(err);
+		return 0;
+	}
+
 	/* TODO: Check user buffer, count and fd validity */
 	if (fd < 0 || fd > TASK_FILES_MAX) {
 		l4_ipc_return(-EBADF);