diff --git a/man7/namespaces.7 b/man7/namespaces.7
index c50c45e69..725ebaff6 100644
--- a/man7/namespaces.7
+++ b/man7/namespaces.7
@@ -203,6 +203,11 @@ and
 .BR pid_namespaces (7)),
 so the file may differ from
 .IR /proc/[pid]/ns/pid .
+The symbolic link gains a value only after the first child process
+is created in the namespace.
+(Beforehand,
+.BR readlink (2)
+of the symbolic link will return an empty buffer.)
 .TP
 .IR /proc/[pid]/ns/user " (since Linux 3.8)"
 .\" commit cde1975bc242f3e1072bde623ef378e547b73f91