diff --git a/libc/include/limits.h b/libc/include/limits.h
index 157f7a6..51f4fad 100644
--- a/libc/include/limits.h
+++ b/libc/include/limits.h
@@ -137,6 +137,8 @@
 #include <bits/posix_limits.h>
 
 #define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
+#define LOGIN_NAME_MAX 256
+#define TTY_NAME_MAX 32
 
 #define _POSIX_VERSION 200809L
 #define _POSIX2_VERSION _POSIX_VERSION
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index e024527..8336976 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -118,6 +118,7 @@
 int getresuid(uid_t* __ruid, uid_t* __euid, uid_t* __suid);
 int getresgid(gid_t* __rgid, gid_t* __egid, gid_t* __sgid);
 char* getlogin(void);
+int getlogin_r(char* __buffer, size_t __buffer_size) __INTRODUCED_IN_FUTURE;
 
 long fpathconf(int __fd, int __name);
 long pathconf(const char* __path, int __name);