Index: uspace/lib/posix/include/posix/unistd.h
===================================================================
--- uspace/lib/posix/include/posix/unistd.h	(revision 316795ca7a45ed0fa2047deabebd675b9458618f)
+++ uspace/lib/posix/include/posix/unistd.h	(revision 1165a41982b3e702655a56bd998366ef0f55a919)
@@ -57,4 +57,7 @@
 /* Environment */
 extern char **__POSIX_DEF__(environ);
+
+/* Sleeping */
+extern unsigned int __POSIX_DEF__(sleep)(unsigned int);
 
 /* Login Information */
Index: uspace/lib/posix/source/unistd.c
===================================================================
--- uspace/lib/posix/source/unistd.c	(revision 316795ca7a45ed0fa2047deabebd675b9458618f)
+++ uspace/lib/posix/source/unistd.c	(revision 1165a41982b3e702655a56bd998366ef0f55a919)
@@ -45,4 +45,5 @@
 
 #include "libc/task.h"
+#include "libc/thread.h"
 #include "libc/stats.h"
 #include "libc/malloc.h"
@@ -56,4 +57,19 @@
 char **posix_environ = NULL;
 char *posix_optarg;
+
+/**
+ * Sleep for the specified number of seconds.
+ *
+ * Note that POSIX allows this call to be interrupted and then the return
+ * value represents remaining seconds for the sleep. HelenOS does not offer
+ * such functionality and thus always the whole sleep is taken.
+ *
+ * @param seconds Number of seconds to sleep.
+ * @return Always 0 on HelenOS.
+ */
+unsigned int posix_sleep(unsigned int seconds)
+{
+	return thread_sleep(seconds);
+}
 
 /**