diff --git a/headers/posix/unistd.h b/headers/posix/unistd.h
index 88efb7143f..4874da9fc4 100644
--- a/headers/posix/unistd.h
+++ b/headers/posix/unistd.h
@@ -135,6 +135,7 @@
 #define _SC_REGEXP						62
 #define _SC_SYMLOOP_MAX					63
 #define _SC_SHELL						64
+#define _SC_TTY_NAME_MAX				65
 
 
 /* confstr() constants */
diff --git a/src/system/libroot/posix/unistd/conf.cpp b/src/system/libroot/posix/unistd/conf.cpp
index 1bcc8d1e73..d5c23b595b 100644
--- a/src/system/libroot/posix/unistd/conf.cpp
+++ b/src/system/libroot/posix/unistd/conf.cpp
@@ -87,6 +87,8 @@ __sysconf(int name)
 			return STREAM_MAX;
 		case _SC_SYMLOOP_MAX:
 			return SYMLOOP_MAX;
+		case _SC_TTY_NAME_MAX:
+			return TTY_NAME_MAX;
 		case _SC_TZNAME_MAX:
 			return TZNAME_MAX;
 		case _SC_VERSION: