diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 087f640dc0..1431d2649b 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -536,6 +536,9 @@ WITH ( MODULUS numeric_literal, REM
(See below for an explanation
of the usefulness of this command.)
+
+ This command acquires a SHARE UPDATE EXCLUSIVE lock.
+