diff --git a/man3/ttyslot.3 b/man3/ttyslot.3
index 63388baff..71143b58c 100644
--- a/man3/ttyslot.3
+++ b/man3/ttyslot.3
@@ -43,9 +43,13 @@ Feature Test Macro Requirements for glibc (see
 .ad l
 .BR ttyslot ():
 .RS 4
-_BSD_SOURCE ||
+Since glibc 2.20:
+    _BSD_SOURCE ||
+    _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_\ <\ 500
 .br
-_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_\ <\ 500\ &&\ _XOPEN_SOURCE_EXTENDED
+Glibc 2.19 and earlier:
+    _DEFAULT_SOURCE ||
+    _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_\ <\ 500
 .RE
 .ad b
 .SH DESCRIPTION