diff --git a/man5/proc.5 b/man5/proc.5
index 3da1a1aa7..dba10559c 100644
--- a/man5/proc.5
+++ b/man5/proc.5
@@ -1876,9 +1876,11 @@ this symbolic link is governed by a ptrace access mode
 .B PTRACE_MODE_READ_FSCREDS
 check; see
 .BR ptrace (2).
-.\" FIXME Describe /proc/[pid]/projid_map
-.\"       Added in 3.7
+.TP
+.IR /proc/[pid]/projid_map " (since Linux 3.7)"
 .\"       commit f76d207a66c3a53defea67e7d36c3eb1b7d6d61d
+See
+.BR user_namespaces (7).
 .TP
 .IR /proc/[pid]/seccomp " (Linux 2.6.12 to 2.6.22)"
 This file can be used to read and change the process's