diff --git a/include/unistd.h b/include/unistd.h
index 2bd85a3708f7..c56fb4f11b41 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -365,6 +365,7 @@ long	 sysconf(int);
 pid_t	 tcgetpgrp(int);
 int	 tcsetpgrp(int, pid_t);
 char	*ttyname(int);
+char	*ttyname_r(int, char *, size_t);
 int	 unlink(const char *);
 ssize_t	 write(int, const void *, size_t);
 
diff --git a/lib/libc/gen/Makefile.inc b/lib/libc/gen/Makefile.inc
index af4f0af88aa1..7257fafffc79 100644
--- a/lib/libc/gen/Makefile.inc
+++ b/lib/libc/gen/Makefile.inc
@@ -143,7 +143,7 @@ MLINKS+=tcsetattr.3 cfgetispeed.3 tcsetattr.3 cfgetospeed.3 \
 	tcsetattr.3 cfmakeraw.3 tcsetattr.3 cfsetispeed.3 \
 	tcsetattr.3 cfsetospeed.3 tcsetattr.3 cfsetspeed.3 \
 	tcsetattr.3 tcgetattr.3
-MLINKS+=ttyname.3 isatty.3 ttyname.3 ttyslot.3
+MLINKS+=ttyname.3 isatty.3 ttyname.3 ttyname_r.3 ttyname.3 ttyslot.3
 MLINKS+=tzset.3 tzsetwall.3
 MLINKS+=unvis.3 strunvis.3 unvis.3 strunvisx.3
 MLINKS+=vis.3 strvis.3 vis.3 strvisx.3