diff --git a/share/libc/netdb.h b/share/libc/netdb.h
index d3efadce2b5aacf50d343166accd17fd451b2eee..e58a1ca1f638e050db9ad497c3a2322da280ad5c 100644
--- a/share/libc/netdb.h
+++ b/share/libc/netdb.h
@@ -99,6 +99,14 @@ struct addrinfo
 # define NI_DGRAM	16	/* Look up UDP service rather than TCP.  */
 # define NI_NUMERICSCOPE 32
 
+// Non-POSIX
+#ifndef NI_MAXHOST
+# define NI_MAXHOST 1025
+#endif
+#ifndef NI_MAXSERV
+# define NI_MAXSERV 32
+#endif
+
 # define EAI_BADFLAGS	  -1	/* Invalid value for `ai_flags' field.  */
 # define EAI_NONAME	  -2	/* NAME or SERVICE is unknown.  */
 # define EAI_AGAIN	  -3	/* Temporary failure in name resolution.  */
diff --git a/share/libc/unistd.h b/share/libc/unistd.h
index c0c279864ed3d9f96f2e2da5b868b321a617a4ab..f7cead96aae3269647af9236a9230ee4ccbec876 100644
--- a/share/libc/unistd.h
+++ b/share/libc/unistd.h
@@ -1079,7 +1079,12 @@ extern pid_t        setsid(void);
 */
 extern int          setuid(uid_t uid);
 
-extern unsigned int sleep(unsigned int);
+/*@
+  assigns \result \from seconds;
+  ensures unslept: 0 <= \result <= seconds;
+ */
+extern unsigned int sleep(unsigned int seconds);
+
 extern void         swab(const void *, void *, ssize_t);
 extern int          symlink(const char *, const char *);
 
diff --git a/tests/libc/netdb_c.c b/tests/libc/netdb_c.c
index c2f9a8c9d3440b2ab3533704693e336e39164350..343f21234e09e55b467ba32a66fdcae9585b650b 100644
--- a/tests/libc/netdb_c.c
+++ b/tests/libc/netdb_c.c
@@ -12,14 +12,6 @@
 
 #define BUF_SIZE 500
 
-// Non-POSIX
-#ifndef NI_MAXHOST
-# define NI_MAXHOST 1025
-#endif
-#ifndef NI_MAXSERV
-# define NI_MAXSERV 32
-#endif
-
 int main() {
   struct addrinfo hints;
   struct addrinfo *result, *rp;
diff --git a/tests/libc/unistd_h.c b/tests/libc/unistd_h.c
index 8f0f40681fda9b3925c1fc47c67b7fc35893b381..5bb417437e2cf0245e3cc735ab6b8f0b288cef99 100644
--- a/tests/libc/unistd_h.c
+++ b/tests/libc/unistd_h.c
@@ -104,5 +104,8 @@ int main() {
   r = pipe(pipefd);
   //@ check ok: r == 0 || r == -1;
 
+  int unslept = sleep(42);
+  //@ assert 0 <= unslept <= 42;
+
   return 0;
 }