diff --git a/man3/qecvt.3 b/man3/qecvt.3
index ad78c5485..664565ef1 100644
--- a/man3/qecvt.3
+++ b/man3/qecvt.3
@@ -46,7 +46,12 @@ Feature Test Macro Requirements for glibc (see
 .BR qecvt (),
 .BR qfcvt (),
 .BR qgcvt ():
-_SVID_SOURCE
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    In glibc up to and including 2.19:
+        _SVID_SOURCE
+.fi
 .ad b
 .\" FIXME . The full FTM picture looks to have be something like the
 .\" following mess: