diff --git a/man7/user_namespaces.7 b/man7/user_namespaces.7
index 094f7a6db..0632aff78 100644
--- a/man7/user_namespaces.7
+++ b/man7/user_namespaces.7
@@ -235,6 +235,27 @@ When a process retrieves file user and group IDs via
 .BR stat (2)
 the IDs are mapped in the opposite direction,
 to produce values relative to the process user and group ID mappings.
+
+The initial user namespace has no parent namespace,
+but, for consistency, the kernel provides dummy user and group
+ID mapping files for this namespace.
+Looking at the
+.I uid_map
+file (the
+.I gid_map
+is the same) from a shell in the initial namespace shows:
+
+.in +4n
+.nf
+$ \fBcat /proc/$$/uid_map\fP
+         0          0 4294967295
+.fi
+.in
+
+This mapping tells us
+that the range starting at user ID 0 in this namespace
+maps to a range starting at 0 in the (nonexistent) parent namespace,
+and the length of the range is the largest 32-bit unsigned integer.
 .\"
 .\" ============================================================
 .\"