diff --git a/uudecode.1 b/uudecode.1
index 1eb6d53..3fd62c0 100644
--- a/uudecode.1
+++ b/uudecode.1
@@ -35,6 +35,10 @@ The
 utility is compliant with the
 .St -p1003.1-2008
 specification.
+.Pp
+The
+.Op Fl m
+flag is an extension to that specification.
 .Sh IMPLEMENTATION NOTES
 For safety currently uudecode operates only on regular files and
 stdout. Trying to uudecode to a link, directory, or special file